Effects of Icariside II on corpus cavernosum and major pelvic ganglion neuropathy in streptozotocin-induced diabetic rats.

Diabetic erectile dysfunction is associated with penile dorsal nerve bundle neuropathy in the corpus cavernosum and the mechanism is not well understood. We investigated the neuropathy changes in the corpus cavernosum of rats with streptozotocin-induced diabetes and the effects of Icariside II (ICA II) on improving neuropathy. Thirty-six 8-week-old Sprague-Dawley rats were randomly distributed into normal control group, diabetic group and ICA-II treated group. Diabetes was induced by a one-time intraperitoneal injection of streptozotocin (60 mg/kg). Three days later, the diabetic rats were randomly divided into 2 groups including a saline treated placebo group and an ICA II-treated group (5 mg/kg/day, by intragastric administration daily). Twelve weeks later, erectile function was measured by cavernous nerve electrostimulation with real time intracorporal pressure assessment. The penis was harvested for the histological examination (immunofluorescence and immunohistochemical staining) and transmission electron microscopy detecting. Diabetic animals exhibited a decreased density of dorsal nerve bundle in penis. The neurofilament of the dorsal nerve bundle was fragmented in the diabetic rats. There was a decreased expression of nNOS and NGF in the diabetic group. The ICA II group had higher density of dorsal nerve bundle, higher expression of NGF and nNOS in the penis. The pathological change of major pelvic nerve ganglion (including the microstructure by transmission electron microscope and the neurite outgrowth length of major pelvic nerve ganglion tissue cultured in vitro) was greatly attenuated in the ICA II-treated group (p < 0.01). ICA II treatment attenuates the diabetes-related impairment of corpus cavernosum and major pelvic ganglion neuropathy in rats with Streptozotocin-Induced Diabetes.

Penile prosthesis implantation in Chinese patients with severe erectile dysfunction: 10-year experience.

We retrospectively evaluated the clinical outcome of penile prosthesis implantation (PPI) in Chinese patients with severe erectile dysfunction (SED). From July 2000 to December 2011, 224 patients (mean age: 35.9±11.8 years, range: 20-75 years) with SED underwent PPI by experienced surgeon according to standard PPI procedure at our centre. A malleable prosthesis (AMS 650) was implanted in 45 cases (20.1%), and a three-piece inflatable prosthesis (AMS 700 CXM or AMS 700 CXR) was implanted in 179 cases (79.9%). Surgical outcomes, including postoperative complications, clinical efficacy and couple satisfaction, were evaluated over than 6 months postoperatively using medical record abstraction, IIEF-5, quality of life (QoL) scores, and the patient/partner sexual satisfaction score proposed by Bhojwani et al. Of the 224 patients eligible for the study, 201 subjects (89.7%) completed follow-up. All of patients could perform sexual intercourse post PPI with the mean postoperative IIEF-5 and QoL scores were 20.02±2.32 and 5.28±0.76, respectively, which were significantly improved compared with the preoperative scores (6.29±1.5 and 2.13±0.84, P<0.01). Of the 201 men, mechanical malfunction occurred in four cases (2.0%) and three cases were re-implanted new device, and two cases (1.0%) developed a mild curvature of the penis. Scrotal erosion with infection occurred in one case with diabetes mellitus (0.5%) and required complete removal of the implanted AMS 700 CXM. Satisfactory sexual intercourse at least twice per month was reported by 178 men (88.6%), and overall satisfaction with the PPI surgery was reported by 89.0% of men and 82.5% of partners. Patient satisfaction in the three-piece inflatable prosthesis group was higher than in the malleable prosthesis group (P<0.05). Satisfaction, however, between the types of prostheses, did not differ in the partner survey. PPI is a safe and effective treatment option for Chinese patients with SED and experienced surgeon perform PPI according to standard PPI procedure could reduce the postoperative complications of PPI and could improve patient satisfaction ratio and QoL.

Evaluation of the effect of different doses of low energy shock wave therapy on the erectile function of streptozotocin (STZ)-induced diabetic rats.

To investigate the therapeutic effect of different doses of low energy shock wave therapy (LESWT) on the erectile dysfunction (ED) in streptozotocin (STZ) induced diabetic rats. SD rats (n = 75) were randomly divided into 5 groups (normal control, diabetic control, 3 different dose LESWT treated diabetic groups). Diabetic rats were induced by intra-peritoneal injection of STZ (60 mg/kg) and rats with fasting blood glucose ≥ 300 mg/dL were selected as diabetic models. Twelve weeks later, different doses of LESWT (100, 200 and 300 shocks each time) treatment on penises were used to treat ED (7.33 MPa, 2 shocks/s) three times a week for two weeks. The erectile function was evaluated by intracavernous pressure (ICP) after 1 week washout period. Then the penises were harvested for histological study. The results showed LESWT could significantly improve the erectile function of diabetic rats, increase smooth muscle and endothelial contents, up-regulate the expression of α-SMA, vWF, nNOS and VEGF, and down- regulate the expression of RAGE in corpus cavernosum. The therapeutic effect might relate to treatment dose positively, and the maximal therapeutic effect was noted in the LESWT300 group. Consequently, 300 shocks each time might be the ideal LESWT dose for diabetic ED treatment.

[Comparative study on the effect of highly active antiretroviral therapy (HAART) in patients with HIV infection acquired by blood transfusion and paid plasma donation].

OBJECTIVE: To study the effect of HAART in patients with AIDS acquire by blood transfusion and paid plasma donation. METHODS: All AIDS patients whose disease was caused by blood transfusion and commercial plasma donation came from the domicile of Hebei Province. In the group of cases of blood transfusion in whom the infection was caused by one-time blood transfusion before and after 1995, there were 189 cases, of whom 105 cases on HAART were designated as observation group, and 84 cases who were not on HAART were designated as control group. The group of AIDS patients who were former commercial plasma donors (FCPDs) had 120 patients who were identified in the survey of 1995, of whom 63 cases on HAART were designated as observation group and 57 cases who were not on HAART were as control group. Onset dates were defined as the dates into the queue. Death due to AIDS was regarded as an outcome event. Subjects who were enrolled into the observation group and control group were epidemiologically followed up regularly. Observation was ended on December 31, 2010. RESULTS: Mortality of patients after HAART from groups of FCPDs and blood recipients were 4.42/100 person-years and 6.13/100 person-years, respectively. The survival rates of HAART groups were 80% in FCPDs for 110 months and 72% in blood recipients for 90 months, respectively. Meanwhile the mortality of no HAART groups were 182.05/100 person-years and 250.66/100 person-years, respectively. Mean survival of patients whose disease was caused by plasma donation and blood transfusion were 4 months and 3 months, respectively. CONCLUSIONS: Whether the HIV infection was caused by plasmapheresis or blood transfusion, the effects of HAART did not show difference. HAART cold reduce the death intensity and prolong survival.

[A retrospective cohort study on the natural history of AIDS caused by blood transfusion].

OBJECTIVE: To study the natural history of AIDS, caused by blood transfusion. METHODS: All HIV infections and AIDS patients were from Hebei province, including those infected through blood transfusion around 1995, that were identified as through general census of former commercial plasma donors (FCPDs). Among those objects being observed during the incubation period, 354 had HIV infections (including 142 cases infected via plasmapheresis and 212 cases caused by transfusion) but had not been treated by HAART before the onset of disease. Objects being observed during the survival period, 141 were AIDS patients (including 57 cases infected via plasmapheresis and 84 cases causes by transfusion) but had not been treated by HAART before and after the onset of disease. All infectors and AIDS patients were under follow-up on the progress of illness or death, respectively. RESULTS: By December 31, 2010, the cumulative incidence among HIV infections was 88.70% (314/354), with the incidence density as 9.14/100 person-years (314/3435.75) and the median incubation period was 113 months. Of 142 HIV infections in the blood donation group and 212 infections in the blood transfusion group, the incubation periods were 112 months and 115 months, respectively. All of the 141 patients died 34 months after the onset, with the death-strength as 204.70/100 person-years (141/68.88) and the period of survival was 4 months. Among those 57 FCPDs infections, they were all died 24 months after the onset, with the death-strength as 250.66/100 person-years (57/22.74) and the survival was 3 months. The other 84 infections who were blood recipients, all died 34 months after the onset, with the death-strength as 182.05/100 person-years (84/ 46.14) and the survival was 4 months. CONCLUSION: Through this study, we noticed that the natural history of all the AIDS patients was caused by blood transmission. It was important to evaluate the natural history of HIV epidemics among both FCPDs and blood recipients, occurred before and after 1995.

[Retrospective cohort study on period of incubation and survival among former commercial plasma donors infected with HIV in Hebei province].

OBJECTIVE: To examine the state of incubation period and survival time of former commercial plasma donors (FCPDs) infected with HIV. METHODS: All objects infected with HIV were from Hebei province and found from general investigation for FCPDs in 1995. The infector cohort by 142 cases was used to estimate incubation period. In the infector cohort, the time which infectors entered the cohort was their infection time, which was the middle value of the origin date, which was January 1, 1995. The onset of AIDS was defined as an outcome event. End point of observation was Dec 31, 2010. There were 192 months in all from beginning to end. The AIDS cohort by 57 cases was used to estimate the survival of the patients. In the patient cohort, the time of AIDS onset was defined as the time entering the cohort, and death of AIDS was defined as an outcome event. The cumulative incidence ratio, cumulative mortality, illness intensity and mortality intensity were analyzed through Kaplan-Meier. RESULTS: During the observation period, 123 cases of 142 infectors developed into AIDS, the cumulative incidence was 86.42% (123/142) and the intensity was 8.53/100 person-years and the median time of incubation period was 112.0 months (95%CI: 108.8 - 115.2). The death dates of 57 patients were from 1 to 24 months after onset. The cumulative mortality was 100%, and the intensity was 250.66/100 person-years and the median survival time was 3.0 months (95%CI: 1.8 - 4.2). It was estimated that the median time was 115.0 months (9.6 years) from infection to death. CONCLUSION: The median times of incubation and median survival time were 112.0 and 3.0 months, respectively.

Effects of icariside II on improving erectile function in rats with streptozotocin-induced diabetes.

Icariin and icariside II (ICA II), 2 active components isolated from herba epimedii, have a closely structural relationship. There is evidence that icariin may be useful in the treatment of erectile dysfunction (ED); however, the study on the therapeutic efficacy of ICA II on ED is currently scant. We investigated the effects of ICA II on improving erectile function of rats with streptozocin-induced diabetes. Fifty 8-week-old Sprague-Dawley rats were randomly distributed into normal control and diabetic groups. Diabetes was induced by a one-time intraperitoneal injection of streptozocin (60 mg/kg). Three days later, the diabetic rats were randomly divided into 4 groups including a saline-treated placebo arm and 3 ICA II-treated models (1, 5, and 10 mg/kg/d). After 3 months, penile hemodynamics was measured by cavernous nerve electrostimulation (CNE) with real time intracorporal pressure assessment. Penises were harvested with subsequent histological examination (picrosirius red stain, Hart elastin stain, and immunohistochemical stain) and Western blots to explore the expression of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) and transforming growth factor ß1 (TGFß1)/Smad2 signaling pathways. Diabetes significantly attenuated erectile responses to CNE. Diabetic rats had decreased corpus cavernosum smooth muscle/collagen ratio and endothelial cell content relative to the control group. The ratio of collagen I to III was significantly lower in the corpora of diabetic rats; furthermore, cavernous elastic fibers were fragmented in the diabetic animals. Neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase, and vascular endothelial growth factor were expressed at lower levels in the diabetic group; ICA II-treated diabetic rats had higher expression in the penis relative to placebo-treated diabetic animals. Both the TGFß1/Smad2/connective tissue growth factor (CTGF) signaling pathway and apoptosis were down-regulated in the penis from ICA II-treated rats. ICA II treatment attenuates diabetes-related impairment of penile hemodynamics, likely by increasing smooth muscle, endothelial function, and nNOS expression. ICA II could alter corpus cavernosum fibrous-muscular pathological structure in diabetic rats, which could be regulated by the TGFß1/Smad2/CTGF and NO-cGMP signaling pathways.

Pathology of urethral fibromuscular system related to parturition-induced stress urinary incontinence and TGF-ß1/Smad pathway.

To study pathological changes of fibromuscular system and the role of TGF-ß1/Smad pathway in the urethra of a parturition-induced stress urinary incontinence (SUI) rat model. Twenty-eight 8-week-old Sprague-Dawley female rats at gestational day 16 were used and randomized into two groups: sham group and SUI group. After delivery, rats in the SUI group underwent postpartum vaginal balloon dilation and bilateral ovariectomy. 1 month after ovariectomy, urodynamics was assessed. Histological examination (Masson's trichrome stain, picrosirius red stain, Hart's elastin stain, Gordon & Sweet's stain, and immunohistochemical stain) and Western blot were performed on urethral tissues. Both leak point pressure and maximal bladder capacity were significantly decreased in the balloon-injured ovariectomized rats, compared with the sham rats. Muscle was significantly decreased in the urethra of SUI rats compare with sham rats. Collagen I/III and reticular fibers from SUI group were also significantly lower than sham group. Meanwhile, elastic fibers and reticular fibers showed fragmentation and disorganization indicating impairment in the fibromuscular system in SUI rats. TGF-ß1, MMP-9, and phosphorylated Smad2 (p-Smad2) were expressed significantly higher in SUI than in sham rats. Simulated birth trauma and menopause induced an upregulation of the TGF-ß1/Smad pathway and impairment of the fibromuscular system in the urethra.

Icariin ameliorates streptozotocin-induced diabetic retinopathy in vitro and in vivo.

This study investigated the effect of Icariin (ICA) supplementation on diabetic retinopathy (DR) in a streptozotocin-induced diabetic rat model system. Fifty Sprague Dawley rats were randomly distributed into a control group and a streptozotocin-induced diabetes group. Diabetic rats were randomly divided into two groups; one group received ICA 5 mg/kg/day for 12 weeks by oral gavage; the other group received saline gavage as a placebo. Retinal morphological changes, endothelial markers (RECA), collagen IV (Col-IV), vascular endothelial growth factor (VEGF), and neuropathic changes (Thy-1 and Brn3a expression) of the retinal ganglion cells (RGCs) were investigated. The effects of ICA at various concentrations (0, 10(1), 10(2), 10(3) nmol/mL) on neurite growth were investigated also in retinal ganglion cells (RGC) cultured from both diabetic and normal animals. Numerous pathological changes (deceased expression of RECA, VEGF, Thy-1, and Brn3a as well as decreased Collagen IV and Müller cell content) were noted in the retinal vessels of diabetic rats; these changes were attenuated in diabetic animals that received ICA. ICA enhanced neurite growth in RGC from both normal rats and diabetic rats in a dose dependent fashion. ICA may be useful in the treatment of diabetic retinopathy. Further investigations are indicated.

The TGF-ß1/Smad/CTGF pathway and corpus cavernosum fibrous-muscular alterations in rats with streptozotocin-induced diabetes.

Diabetes-associated erectile dysfunction is associated with increased extracellular matrix deposition and reduced smooth muscle content in the corpus cavernosum. The mechanisms of these processes are not well understood. In this study, we investigated fibromuscular changes in the corpus cavernosum of rats with streptozotocin-induced diabetes to determine the mechanisms underlying pathologic changes in penile structure and function. Forty 8-week-old Sprague-Dawley rats were randomly distributed into control and diabetic groups. Diabetes was induced by a one-time intraperitoneal injection of streptozotocin 60 mg/kg. Twelve weeks later, erectile function was measured by cavernous nerve electrostimulation with real-time intracorporal pressure assessment. The penis was harvested for histologic examination (Masson trichrome stain, picrosirius red stain, Hart elastin stain, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, and immunohistochemistry) and Western blot. Diabetes significantly attenuated erectile response to cavernous nerve electrostimulation. Diabetic animals exhibited a decreased smooth muscle/collagen ratio in the corpus cavernosum. The ratio of collagen I to II fibers was significantly lower in the corpora of diabetic rats compared with controls. Cavernous elastic fibers were fragmented in diabetic rats. There was up-regulation of the transforming growth factor ß1/Smad/connective tissue growth factor signaling pathway in diabetic rats. Phospho-Smad2 expression was higher in smooth muscle cells and fibroblasts of diabetic rats, as was the apoptotic index. The up-regulation of the transforming growth factor ß1/Smad/connective tissue growth factor signaling pathway might play an important role in diabetes-induced fibrous-muscular structural changes and deterioration of erectile function.

[Changes in morphology and steroidogenic function of aged human Leydig cells].

OBJECTIVE: To investigate the changes of morphology and steroidogenic function in aged human Leydig cells and to understand the mechanism of late onset hypogonadism (LOH). METHODS: Ten young and ten aged male subjects were enrolled in this study. AMS (Aging Male's Symptoms) scale was used for symptom evaluation. Testes species with LOH were utilized as the research model. Then the histological changes in testis and ultrastructure of Leydig cells were observed by HE staining and electron microscopy (EM), respectively. The serum total testosterone concentrations were measured by an ELISA kit. The expressions of steroidogenic acute regulatory (StAR) protein and cholesterol-side-chain cleavage enzyme (P450scc) were detected by western blot. RESULTS: The scores of AMS in the aged group were higher than those in the young group with decreased serum testosterone levels (61.25 ± 7.08 vs. 20.75 ± 3.73,P<0.001). And the serum testosterone level of the aged human was lower than that of the young human [(3.12 ± 0.58) µg/L vs. (6.29 ± 1.17) µg/L,P<0.05]. HE staining showed that degenerative changes occurred in the aged human testes. And many swollen mitochondria with mitochondrial cristae that disappeared were found in Leydig cells of the aged human by EM. The serum total testosterone level of the aged human was significantly lower than that of the young group. And the expressions of StAR and P450scc protein in the aged group were significantly lower than those of the young group. CONCLUSION: Mitochondrial swelling and decreased expressions of StAR and P450scc were closely related to the reduced ability of testosterone synthesis in aged males. And the exact mechanism needs further investigation.

[Retrospective cohort study on the rate of mother-to-child transmission among mothers infected with human immunodeficiency virus type 1 through blood transfusion].

OBJECTIVE: To study the rate of mother-to-child transmission (MTCT) on HIV-1. METHODS: All local residents from 8 townships in a region were screened for mothers who had a history of only one blood transfusion and 63 were found HIV-1 positive. A further study on these HIV-1 positive mothers and their children was conducted with the emphasis on the date of receiving blood transfusion, date and type of nationality, history regarding breastfeeding and so on. Sera specimens from 84 children born from 63 HIV-1 positive mothers were screened, using ELISA for HIV-1 antibody, and positive specimens were confirmed by Western-blot. RESULTS: The rate of MTCT was 32.1% (27/84) for children with all risk factors related to MTCT. Another 36.8% (7/19) were related to factors on intrauterine, intrapartum and breastfeeding, 35.7% (5/14) to intrapartum and breastfeeding factors, 14.3% (2/14) to intrauterine and intrapartum factors, 37.9% (11/29) to breastfeeding factor alone. By group combination analysis, the MTCT rate was 36.9% (24/65) with breastfeeding, 11.8% (2/17) with artificial feeding, and the former was significantly higher than the latter. CONCLUSION: HIV-1 MTCT rate among mothers caused by a single blood transfusion varied with different risk factors. Breastfeeding played an important role in MTCT, appeared in our study.

[Investigation on status of HIV-1 infection among blood recipients from 1994 to 1998 in certain areas of China].

OBJECTIVE: To study the infection status of HIV-1 among blood recipients from 1994 to 1998 in certain areas of Hebei province. METHODS: A general investigation was set up among all the people in 15 townships of certain areas from November 2003 to February 2005. An epidemiological investigation was conducted among people who had received blood from donors, during 1994 and 1998. Blood samples were collected. ELISA was used in preliminary screening and Western-blot (WB) was used among people who showed a positive result in the preliminary screening. RESULTS: The infection rate of HIV-1 after blood receipt was 15.54% (92/592), and the infected persons were all appeared in five medical centers of 6 townships which located at the west part of the area. HIV-1 infection happened over the years, and reaching the zenith in the year 1995. Most of the infected persons were young women. Procreation was the main cause of blood transfusion for women and trauma was for men. CONCLUSION: A typical HIV outbreak happened in certain areas after blood transfusion in Hebei.

[Following surveillance on HIV infection after blood transfusion].

OBJECTIVE: To study epidemiological features of HIV infection after blood transfusion and the situation of transmission among members of family. METHODS: The persons infected with HIV through blood transfusion and their intrafamilial transmission in some city were analyzed and testing methods of ELISA, Western-blot, RT-PCR and subtype analyzing were used. The whole surveillance data came from residents investigation around problem medical centres and HIV monitoring network around Hebei province. RESULTS: 173 people infected with HIV after blood transfusion in some city, including 89 cases found in hospital and 84 cases in CDC, accounted for 68.7% (173/252) of all of infected persons by blood transfusion in Hebei province. The rate of intrafamilial transmission, spousal transmission and mother-to-child transmission((MTCT) were 32.0% (49/153),17.0% (26/153) and 32.7% (32/98), respectively. Most of persons infected with HIV were youth among who the female were more than the male. Childbearing and women's ailments were the main cause of blood transfusion from 1990 to 1999, and traumatism surgery took second place. Infected persons by HIV blood, whose time to diagnostic were the year from 1999 to 2009, spread over Kangtai hospital and other hospital which accounted for 45.1% (78/173) and 42.2% (73/173), respectively. The genetype of all patients were B' subtype. CONCLUSION: The medical centers at the grass-roots level in some city resulted in outbreak of infected persons by HIV blood because of having no screening test antibody of HIV for liid blood donors.

Stimulation of ANP secretion by 2-Cl-IB-MECA through A(3) receptor and CaMKII.

Adenosine is a potent mediator of myocardial protection against hypertrophy via A(1) or A(3) receptors that may be partly related to atrial natriuretic peptide (ANP) release. However, little is known about the possible involvement of the A(3) receptor on ANP release. We studied the effects of the A(3) receptor on atrial functions and its modification in hypertrophied atria. A selective A(3) receptor agonist, 2-chloro-N(6)-(3-iodobenzyl) adenosine-5'-N-methyluronamide (2-CI-IB-MECA), was perfused into isolated, beating rat atria with and without receptor modifiers. 2-CI-IB-MECA dose-dependently increased the ANP secretion, which was blocked by the A(3) receptor antagonist, but the increased atrial contractility and decreased cAMP levels induced by 30muM 2-CI-IB-MECA were not affected. The 100muM 2-(1-hexylnyl)-N-methyladenosine (HEMADO) and N(6)-(3-iodobenzyl) adenosine-5'-N-methyluronamide (IB-MECA), A(3) receptor agonist, also stimulated the ANP secretion without positive inotropy. The potency for the stimulation of ANP secretion was 2-CI-IB-MECA>>IB-MECA=HEMADO. The inhibition of the ryanodine receptor or calcium/calmodulin-dependent kinase II (CaMKII) attenuated 2-CI-IB-MECA-induced ANP release, positive inotropy, and translocation of extracellular fluid. However, the inhibition of L-type Ca(2+) channels, sarcoplasmic reticulum Ca(2+)-reuptake, phospholipase C or inositol 1,4,5-triphosphate receptors did not affect these parameters. 2-CI-IB-MECA decreased cAMP level, which was blocked only with an inhibitor of CaMKII or adenylyl cyclase. These results suggest that 2-CI-IB-MECA increases the ANP secretion mainly via A(3) receptor activation and positive inotropy by intracellular Ca(2+) regulation via the ryanodine receptor and CaMKII.

Attenuation of hypoosmotic stress-induced ANP secretion via I(Cl,swell) in renal hypertensive rat atria.

Cardiac hypertrophy, an adaptive process to an increased hemodynamic overload, includes not only an increase in cell size but also qualitative changes in constituent proteins. Although swelling-activated chloride channels (I(Cl,swell)) chronically activate in hypertrophied atrial myocytes, the role of I(Cl,swell) in regulation of atrial natriuretic peptide (ANP) release is poorly understood. We investigated the effects of I(Cl,swell) on ANP release and contractility and its modification in hypertrophied rat atria. To stimulate I(Cl,swell), hypoosmotic HEPES buffered solution (0.8T, 0.7T and 0.6T) was perfused into isolated perfused beating atria. The hypoosmotic HEPES buffered solution increased ANP release as compared to isoosmotic buffered solution (1T) in an osmolarity-reduction dependent manner. Atrial contractility and extracellular fluid translocation did not change. Exposure to hypoosmotic buffer (0.8T) containing low chloride (8mM), tamoxifen or diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) significantly attenuated hypoosmolarity-induced ANP release. The pretreatment with genistein, okdaic acid, U73122, GF109203x, and staurosporine attenuated hypoosmolarity-induced ANP release whereas orthovanadate augmented it significantly. In hypertrophied atria from renal hypertensive rats, hypoosmolarity-induced ANP release was markedly attenuated and DIDS-induced decrease in ANP release and negative inotropy were augmented as compared to sham-operated rat atria. Therefore, we suggest that I(Cl,swell) may partly participate hypoosmolarity-induced ANP release through protein tyrosine kinase and phospholipase C-protein kinase C pathway. The modification of responses of ANP release to hypoosmolarity and DIDS in hypertrophied atria may relate to changes in I(Cl,swell) activity by persistent high blood pressure.

Regulation of stretch-activated ANP secretion by chloride channels.

This study was aimed to define roles of stretch-activated ion channels (SACs), especially Cl(-) channels, in regulation of atrial natriuretic peptide (ANP) secretion using isolated perfused beating atria. The volume load was achieved by elevating height of outflow catheter connected to isolated rat atria and the pressure load was achieved by decreasing diameter of outflow catheter. Both methods increased atrial contractility similarly although volume load was different (736microl for volume load vs. 129microl for pressure load). Atrial stretch by volume load markedly increased ECF translocation and ANP secretion but the pressure load slightly increased. The ANP secretion was positively correlated to workload generated by volume or pressure load. Treatment of atria with gadolinium, a blocker for SACs, attenuated the ECF translocation and the ANP secretion induced by volume load. A blocker for Ca2+-activated Cl(-) channel, niflumic acid (NFA), accentuated the ANP secretion induced by volume load whereas a blocker for swelling-activated Cl(-) channel, diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS), attenuated the ANP secretion. The ANP secretion of hypertrophied atria by volume load was markedly reduced and the augmented effect of NFA on volume load-induced ANP secretion was not observed. These results indicate that Cl(-) channels may differently regulate stretch-activated ANP secretion.

Different regulation of atrial ANP release through neuropeptide Y2 and Y4 receptors.

Neuropeptide Y (NPY) receptors are present in cardiac membranes. However, its physiological roles in the heart are not clear. The aim of this study was to define the direct effects of pancreatic polypeptide (PP) on atrial dynamics and atrial natriuretic peptide (ANP) release in perfused beating atria. Pancreatic polypeptides, a NPY Y(4) receptor agonist, decreased atrial contractility but was not dose-dependent. The ANP release was stimulated by PP in a dose-dependent manner. GR 23118, a NPY Y(4) receptor agonist, also increased the ANP release and the potency was greater than PP. In contrast, peptide YY (3-36) (PYY), an NPY Y(2) receptor agonist, suppressed the release of ANP with positive inotropy. NPY, an agonist for Y(1, 2, 5) receptor, did not cause any significant changes. The pretreatment of NPY (18-36), an antagonist for NPY Y(3) receptor, markedly attenuated the stimulation of ANP release by PP but did not affect the suppression of ANP release by PYY. BIIE0246, an antagonist for NPY Y(2) receptor, attenuated the suppression of ANP release by PYY. The responsiveness of atrial contractility to PP or PYY was not affected by either of the antagonists. These results suggest that NPY Y(4) and Y(2) receptor differently regulate the release of atrial ANP.

Diadenosine tetraphosphate stimulates atrial ANP release via A(1) receptor: involvement of K(ATP) channel and PKC.

Diadenosine polyphosphates (APnAs) are endogenous compounds and exert diverse cardiovascular functions. However, the effects of APnAs on atrial ANP release and contractility have not been studied. In this study, the effects of diadenosine tetraphosphate (AP4A) on atrial ANP release and contractility, and their mechanisms were studied using isolated perfused rat atria. Treatment of atria with AP4A resulted in decreases in atrial contractility and extracellular fluid (ECF) translocation whereas ANP secretion and cAMP levels in perfusate were increased in a dose-dependent manner. These effects of AP4A were attenuated by A(1) receptor antagonist but not by A(2A) or A(3) receptor antagonist. Other purinoceptor antagonists also did not show any effects on AP4A-induced ANF release and contractility. The increment of ANP release and negative inotropy induced by AP4A was similar to those induced by AP3A, AP5A, and AP6A. Protein kinase A inhibitors accentuated AP4A-induced ANP secretion. In contrast, an inhibitor of phospholipase C, protein kinase C or sarcolemma K(ATP) channel completely blocked AP4A-induced ANP secretion. However, an inhibitor of adenylyl cyclase or mitochondria K(ATP) channel had no significant modification of AP4A effects. These results suggest that AP4A regulates atrial inotropy and ANP release mainly through A(1) receptor signaling involving phospholipase C-protein kinase C and sarcolemmal K(ATP) channel and that protein kinase A negatively modulates the effects of AP4A.

The effect of papaverine on ion channels in rat basilar smooth muscle cells.

OBJECTIVES: Papaverine has been used in treating vasospasm following subarachnoid hemorrhage (SAH). However, its action mechanism for cerebral vascular relaxation is not clear. Potassium and calcium channels are closely related to the contraction and relaxation of cerebral smooth muscle. Therefore, to identify the role of potassium and calcium channels in papaverine-induced vascular relaxation, we examined the effect of papaverine on potassium and calcium channels in freshly isolated smooth muscle cells from rat basilar artery. METHOD: The isolation of rat basilar smooth muscle cells was performed by special techniques. The whole cell currents were recorded by whole cell patch clamp technique in freshly isolated smooth muscle cells from rat basilar artery. Papaverine was added to the bath solution. RESULTS: Papaverine of 100 microM into bath solution increased the amplitude of the outward K(+) current which was completely blocked by BKCa blocker, IBX (iberiotoxin) and a calcium chelator, BAPTA (1,2-bis(o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid) in whole cell mode. Papaverine (100 microM) also inhibited L type Ca(2+) current recorded in isolated smooth muscle cells from rat basilar artery. DISCUSSION: These results strongly suggest that Ca(2+)-activated potassium channels and L type Ca(2+) channels may be involved in papaverine-induced vascular relaxation in rat basilar artery.