Salusin ß Within the Nucleus Tractus Solitarii Suppresses Blood Pressure Via Inhibiting the Activities of Presympathetic Neurons in the Rostral Ventrolateral Medulla in Spontaneously Hypertensive Rats.

Salusin ß is a newly identified bioactive peptide, which shows peripheral hypotensive, mitogenic and proatherosclerotic effects. The present study was undertaken to investigate the role of salusin ß within the nucleus tractus solitarii (NTS) and the underlying mechanism in regulating blood pressure and heart rate (HR) in spontaneously hypertensive rats (SHR). Our results showed that bilateral or unilateral microinjection of salusin ß (0.4-40 pmol) into the NTS in SHR decreased mean arterial pressure and HR in a dose-dependent manner. Bilateral microinjection of salusin ß (4 pmol) within NTS improved baroreflex sensitivity functions in SHR. Pretreatment with glutamate receptors antagonist kynurenic acid (5 nmol) into the NTS in SHR did not alter the salusin ß (4 pmol) induced hypotension and bradycardia. Likewise, bilateral vagotomy also did not alter the salusin ß (4 pmol) induced hypotension and bradycardia. However, pretreatment with GABAA receptors agonist muscimol (100 pmol) within the rostral ventrolateral medulla (RVLM) in SHR almost completely abolished the hypotension and bradycardia evoked by intra-NTS salusin ß (4 pmol). Our findings suggested that microinjection of salusin ß into the NTS produced hypotension and bradycardia, as well as improved baroreflex sensitivity functions, via inhibiting the activities of presympathetic neurons in the RVLM in SHR.

Actions of genistein on contractile response of smooth muscle isolated from guinea pig gallbladder.

BACKGROUND: Defective contractile motility of the gallbladder is an important factor for gallstone formation. Estrogen might increase the risk of gallstones and cholecystitis, and estradiol inhibits the contractile activity of isolated strips of guinea pig gallbladder. The potential risks associated with hormone replacement therapy (HRT) include symptomatic gallstones. Phytoestrogen have been used to treat menopause syndromes by replacing traditional estrogen. This experiment aimed to determine the effects of the phytoestrogen genistein on the contractile response of smooth muscle strips isolated from guinea pig gallbladder and its possible mechanism of action. METHODS: Guinea pigs were sacrificed to remove the whole gallbladder. Two or three smooth muscle strips were cut longitudinally. Each strip was suspended in a tissue chamber containing Krebs solution. After 2 hours of equilibration, contractile response indexes were recorded. Different concentrations of genistein were added to the chamber and the contractile responses were measured. Each antagonist was added 2 minutes before genistein to study possible mechanisms. The effect of genistein on calcium-dependent contraction curves and biphasic contraction in calcium-free Krebs solution were measured. RESULTS: Genistein decreased the resting tension dose-dependently, and reduced the mean contractile amplitude and frequency in gallbladder strips. Ranitidine partly inhibited the effect of genistein, but methylene blue, Nomega-nitro-L-arginine, and propranolol hydrochloride did not influence this action. Genistein had no significant effects on calcium-dependent contraction. Genistein reduced the first contraction induced by acetylcholine chloride, but did not affect the second contraction caused by CaCl2. CONCLUSIONS: Genistein relaxed smooth muscle isolated from the gallbladder of guinea pigs and this might contribute to the formation of gallstones. The inhibitory action might be related to H2 receptors and the release of intracellular Ca2+ from sarcoplasmic reticulum. Replacing traditional estrogen with phytoestrogen to treat menopause syndromes may increase the risk of gallstone formation.

Effect of Fructus Psoraleae on motility of gallbladder isolated smooth muscle strips from guinea pigs.

AIM: To observe the effect of Fructus Psoraleae on motility of isolated gallbladder muscle strips of guinea pigs and its mechanism. METHODS: Guinea pigs were hit to lose consciousness and the whole gallbladder was removed quickly. Two or three smooth muscle strips (8 mm x 3 mm) were cut along a longitudinal direction. The mucosa was gently removed. Every longitudinal muscle strip was suspended in a tissue chamber which was continuously perfused with 5 mL Krebs solution (37 degrees of C), pH 7.4, and aerated with 950 mL/L O2 and 50 mL/L CO2. The isometric response was recorded with an ink-writing recorder. After 2 h equilibration under 1 g-load, 50 microL Fructus Psoraleae (10, 20, 70, 200, 700, 1000 g/L) was added cumulatively into the tissue chamber in turn every 2 min to observe their effects on gallbladder muscle strips (cumulating final concentration of Fructus Psoraleae was 0.1, 0.3, 1.0, 3.0, 10.0, 20.0 g/L). The antagonists, including 4-DAMP, benzhydramine, hexamethonium, phentolamine, verapamil and idomethine were given 2 min before Fructus Psoraleae respectively to investigate the mechanisms involved. RESULTS: Fructus Psoraleae dose-dependently increased the resting tension (r = 0.992, P < 0.001), decreased the mean contractile amplitude (r = 0.970, P < 0.001) and meanwhile increased the contractile frequency of the gallbladder muscle strip in vitro (r = 0.965, P < 0.001). The exciting action of Fructus Psoraleae on the resting tension could be partially blocked by 4-DAMP (the resting tension decreased from 1.37 +/- 0.41 to 0.70 +/- 0.35, P < 0.001), benzhydramine (from 1.37 +/- 0.41 to 0.45 +/- 0.38, P < 0.001), hexamethonium (from 1.37 +/- 0.41 to 0.94 +/- 0.23, P < 0.05), phentolamine ( from 1.37 +/- 0.41 to 0.89 +/- 0.22, P < 0.01) and verapamil (from 1.37 +/- 0.41 to 0.94 +/- 0.26, P < 0.05). But the above antagonists had no significant effect on the action of Fructus Psoraleae-induced mean contractile amplitude (P > 0.05). Moreover, the increase of the contractile frequency due to Fructus Psoraleae was inhibited by 4-DAMP (decreased from 8.3 +/- 1.2 to 6.8 +/- 0.5, P < 0.01) and hexamethonium (from 8.3 +/- 1.2 to 7.0 +/- 0.9, P < 0.05). Idomethine had no significant effect on the Fructus Psoraleae-induced responses (P > 0.05). CONCLUSION: Fructus Psoraleae enhances the motility of isolated gallbladder muscle strips from guinea pigs, in a dose-dependent manner. The effect of Fructus Psoraleae is partly related to M3, N receptor, alpha receptor, H1 receptor, Ca2+ channel, but not related to prostaglandin.

Proanthocyanidin from grape seeds potentiates anti-tumor activity of doxorubicin via immunomodulatory mechanism.

The purpose of this study was to investigate the anti-tumor activities of proanthocyanidin (PA) from grape seeds and doxorubicin (DOX) in vitro as well as in vivo, either alone or in combination and to explore the immunomodulatory mechanism in tumor-bearing mice. PA (12.5 approximately 200 mg/l) or DOX (0.01 approximately 1 mg/l) for 24 h significantly inhibited YAC-1 cell proliferation (IC(50) 57.53 or 0.198 mg/l, respectively) in a concentration-dependent manner using microculture tetrazolium (MTT) assay. Meanwhile, a combination of PA (12.5, 25 mg/l) with DOX strongly inhibited cell proliferation with IC(50) values of DOX decreasing by 0.09 and 0.045 mg/l, respectively. In mouse tumor xenograft models, intraperitoneal administrations of PA (10 mg/kg) daily or DOX (2 mg/kg) every other day for 9 days significantly inhibited the growth of sarcoma 180, whereas a combination of the two strongly inhibited tumor growth as compared with PA or DOX alone (p<0.01). In contrast to PA treatment, DOX inhibited Con A-stimulated lymphocyte proliferation, IL-2 and IFN-gamma productions, NK cell cytotoxicity and CD4+/CD8+ ratio, while the administration of PA combined with DOX significantly enhanced the above immune responses as compared with the tumor-bearing control (p<0.01). Taken together, these results suggest that PA has anti-tumor activity and increases the anti-tumor activity of DOX, and the mechanism might be related partially to immunopotentiating activities through the enhancements of lymphocyte proliferation, NK cell cytotoxicity, CD4+/CD8+ ratio, IL-2 and IFN-gamma productions.

Effects of rhubarb on isolated gastric muscle strips of guinea pigs.

AIM: To study the effects of rhubarb (dried root of Rheum officinale Baill.) on contractile activity of isolated gastric muscle strips of guinea pigs and its possible mechanism. METHODS: A total of 48 guinea pigs were killed to remove the whole stomach. Then, the stomach was opened and the mucosal layer was removed. Parallel to the circular fibers, muscle strips were cut from the body. Each isolated gastric muscle strip was suspended in a tissue chamber containing 5 mL Krebs solution, constantly warmed by water jacket at 37 degrees and bubbled continuously with a mixed gas of 950 mL/L O2 and 50 mL/L CO2. After being incubated for 1 h with 1 g tension, rhubarb of varied concentrations (1%, 2%, 7%, 20% and 70%) was added cumulatively into the tissue chamber at intervals of 2 min. Atropine (10(-6) mol/L) or isoptin (5 x 10(-8) mol/L) or hexamethonium (10(-5) mol/L) was given 2 min before the administration of rhubarb. The isometrical response was measured with an ink-writing recorder. RESULTS: Rhubarb dose dependently increased the resting tension of gastric body circular muscle (CM) (r = 0.726, P<0.05). Atropine (r = 0.829, P<0.05), isoptin (r = 0.764, P<0.05) and hexamethonium (r = 0.797, P<0.05) did not affect its action in a dose-related manner. Atropine apparently reduced the increasing action of 1%, 3%, 10%, 30% and 100% rhubarb on the resting tension of gastric body CM. Isoptin inhibited the effect of 10%, 30% and 100% rhubarb on the resting tension of gastric body CM. Hexamethonium reduced the increasing action of 1%, 10%, 30% and 100% rhubarb on the resting tension of gastric body CM. Rhubarb increased the contractile frequency of CM of body. While atropine, isoptin and hexamethonium did not inhibit the contractile frequency of gastric body CM in comparison with rhubarb at the same concentration, rhubarb at the highest concentration (100%) decreased the mean contractile amplitude of gastric body CM. Atropine, isoptin and hexamethonium did not affect the mean contractile amplitude of gastric body CM compared to rhubarb at the same concentration. CONCLUSION: Rhubarb has exciting actions on isolated gastric smooth muscle strips of guinea pig. The exciting action of rhubarb is partly mediated via cholinergic M receptor, cholinergic N receptor and L-type calcium channel.

Effect of rhubarb on contractile response of gallbladder smooth muscle strips isolated from guinea pigs.

AIM: To investigate the effect of rhubarb on contractile response of isolated gallbladder muscle strips from guinea pigs and its mechanism. METHODS: Guinea pigs were killed to remove the whole gallbladder. Two or three smooth muscle strips (8 mm x 3 mm) were cut along the longitudinal direction. The mucosa on each strip was carefully removed. Each longitudinal muscle strip was suspended in a tissue chamber containing 5 mL Krebs solution (37 degrees), bubbled continuously with 950 mL/L O(2) and 50 mL/L CO(2). The resting tension (g), mean contractile amplitude (mm), and contractile frequency (waves/min) were simultaneously recorded on recorders. After 2-h equilibration, rhubarb (10, 20, 70, 200, 700, 1,000 g/L) was added cumulatively to the tissue chamber in turns every 2 min to observe their effects on gallbladder. Antagonists were given 3 min before administration of rhubarb to investigate the possible mechanism. RESULTS: Rhubarb increased the resting tension (from 0 to 0.40+/-0.02, P<0.001), and decreased the mean contractile amplitude (from 5.22+/-0.71 to 2.73+/-0.41, P<0.001). It also increased the contractile frequency of the gallbladder muscle strips in guinea pigs (from 4.09+/-0.46 to 6.08+/-0.35, P<0.001). The stimulation of rhubarb on the resting tension decreased from 3.98+/-0.22 to 1.58+/-0.12 by atropine (P<0.001), from 3.98+/-0.22 to 2.09+/-0.19 by verapamil (P<0.001) and from 3.98+/-0.22 to 2.67+/-0.43 by phentolamine (P<0.005). But the effect was not inhibited by hexamethonium (P>0.05). In addition, the action of mean amplitude and frequency was not inhibited by the above antagonists. CONCLUSION: Rhubarb can stimulate the motility of isolated gallbladder muscle strips from guinea pigs. The stimulation of rhubarb might be relevant with M receptor, Ca(2+) channel and alpha receptor partly.

[Effects of proanthocyanidins on contractile activity of aortic smooth muscle and platelet aggregation in experimental animals].

AIM: To study effects of proanthocyanidins (PA) on contractile activity of isolated aortic smooth muscle in rats and rabbit platelet aggregation. METHODS: Isolated rat aortic muscle rings were adopted to observe the effects of PA on their contraction induced by noradrenaline (NA) or KCl, and their tensions were recorded by BL-310 experimental system of biological function. Rabbit platelet aggregation induced by arachidonic acid (AA), adenosine diphosphate (ADP), and collagen (Coll) was assayed by turbidimetry. RESULTS: PA could significantly inhibit the contraction induced by NA (10(-6) mol/L), low the concentration-response curves of NA and the maximal response on the endothelium-intact or endothelium-denuded aortic rings. But PA couldn't relax the aortic rings precontracted with KCl and had no influence on rabbit platelet aggregation induced by AA, ADP, and Coll. CONCLUSION: PA can inhibit the contraction induced by NA but not by KCl on isolated rat aortic rings. It also has no influence on rabbit platelet aggregation.

Action of progesterone on contractile activity of isolated gastric strips in rats.

AIM: To study the effect of progesterone on contractile activity of isolated gastric strips in rats. METHODS: Wistar rats were sacrificed to remove whole stomach. Then, the stomach was opened and the mucosal layer was removed. Parallel to either the circular or the longitudinal fibers, muscle strips were cut from fundus, body, antrum and pylorus. Each muscle strip was suspended in a tissue chamber containing 5 mL Krebs solution. Then the motility of gastric strips in tissue chambers was simultaneously recorded. The preparations were subjected to 1 g load tension and washed with 5 ml Krebs solution every 20 min. After 1 h equilibration, progesterone or antagonists were added in the tissue chamber separately. The antagonists were added 3 min before using progesterone (50 micromol/L(-1)). RESULTS: Progesterone decreased the resting tension of fundus and body longitudinal muscle (LM) (P<0.05). It inhibited the mean contractile amplitude of body and antrum LM and circular muscle (CM), and the motility index of pyloric CM (P<0.05). The inhibition of progesterone on the mean contractile amplitude could be partially blocked by phentolamine in LM of the stomach body (the mean contractile amplitude of body LM decreased from -7.5+/-5.5 to -5.2+/-4.5 P<0.01), and by phentolamine or indomethacin in CM of body (The inhibition of progesterone on the mean contractile amplitude of body CM decreased from -5.6+/-3.0 to -3.6+/-2.7 by phentolamine and from -5.6+/-3.0 to -3.5+/-2.5 by indomethacin, P<0.01). Hexamethonium, propranolol and L-NNA (inhibitor of NO synthetase) didn't affect the action of progesterone (P>0.05). CONCLUSION: The study suggested that progesterone can inhibit the contractile activity of isolated gastric strips in rats and the mechanism seems to be a direct one except that the action on gastric body is mediated through prostaglandin and adrenergic alpha receptor partly.

Effect of areca on contraction of colonic muscle strips in rats.

AIM: To investigate the effects of areca on the contractile activity of isolated colonic muscle strips in rats and mechanism involved. METHODS: Each strip (LMPC, longitudinal muscle of proximal colon; CMPC, circular muscle of proximal colon; LMDC, longitudinal muscle of distal colon; CMDC, circular muscle of distal colon.) was suspended in a tissue chamber containing 5 mL Krebs solution (37 degrees C), bubbled continuously with 950 mL.L(-1) O(2) and 50 mL.L(-1) CO(2). The mean contractile amplitude (A), the resting tension (T), and the contractile frequency (F) were simultaneously recorded on recorders. RESULTS: Areca dose dependently increased the mean contractile amplitude, the resting tension of proximal and distal colonic smooth muscle strips in rats (P<0.05). It also partly increased the contractile frequency of colonic smooth muscle strips in rats (P<0.05). The effects were partly inhibited by atropine (the resting tension of LMPC decreased from 0.44 +/- 0.12 to 0.17 +/- 0.03; the resting tension of LMDC decreased from 0.71 +/- 0.14 to 0.03 +/- 0.01; the mean contractile amplitude of LMPC increased from -45.8 +/- 7.2 to -30.5 +/- 2.9; the motility index of CMDC decreased from 86.6 +/- 17.3 to 32.8 +/- 9.3; P<0.05 vs areca), but the effects were not inhibited by hexamethonium (P>0.05). CONCLUSION: Areca stimulated the motility of isolated colonic smooth muscle strips in rats. The stimulation of areca might be relevant with M receptor partly.

Inhibition of beta-estradiol on trachea smooth muscle contraction in vitro and in vivo.

AIM: To investigate the effect of beta-estradiol on trachea smooth muscle contraction in vitro and in vivo. METHODS: (1) Rabbit tracheas were incubated in organ baths filled with Krebs solution and supplied with a mixed gas of 95 % O2 and 5 % CO2. The isometric force was measured by ink-writing recorders. (2) The incubation period of asthma induced by histamine and acetylcholine (ACh) in guinea pig were measured before and after beta-estradiol (1 mg/kg) were given intramuscularly. RESULTS: (1) Administration of beta-estradiol (0.1 mmol/L) caused relaxation of isolated trachea muscle strips (TMS) in rabbits pre-contracted by ACh and KCl (39 % +/- 5 % and 45 % +/- 19 %). The presence of indomethacin or methylene blue partly decreased the relaxation to beta-estradiol (26 % +/- 8 % and 28 % +/- 13 %), but Nomega-nitro-L-arginine (L-NNA) and propranolol and epithelium removal did not affect it (38 % +/- 10 %, 40 % +/- 15 %, 37 % +/- 8 %). beta-Estradiol can shifted the concentration-response curves of ACh and CaCl2 to the rightward (pD2 = 3.98 and 4.75). In addition, it could also significantly inhibit the contraction of phase caused by ACh, but did not affect the contraction of phase II caused by CaCl2. (2) The incubation period of asthma in guinea pig were delayed by beta-estradiol (1 mg/kg) given intramuscularly. CONCLUSION: (1) The relaxation of beta-estradiol in vitro was epithelium independent and associated with the inhibition of potential-dependent channel and release of Ca2+ from sarcoplasm reticulum induced by ACh. In addition, release of prostaglandins from trachea smooth muscle cells and relaxation through cGMP approach were also included. beta-Adrenoceptor-mediated relaxation was not involved. (2) beta-Estradiol can relax the trachea in vivo in guniea pig.

Effect of cholecystokinin and secretin on contractile activity of isolated gastric muscle strips in guinea pigs.

AIM:To study the effect of cholecystokinin-octapeptide (CCK-8) and secretin on contractile activity of isolated gastric muscle strips in guinea pigs.METHODS:Each isolated gastric muscle strip was suspended in a tissue chamber containing 5mL Krebs solution constantly warmed by water jacked at 37° and supplied with a mixed gas of 95% O(2) and 5% CO(2). After incubating for 1h under 1g tension, varied concentrations of CCK-8 and secretin were added respectively in the tissue chamber and the contractile response was measured isometrically on ink-writing recorders.RESULTS:CCK-8 could increase (1) all regional circular and longitudinal muscular tension at rest (fundus LM 19.7% ± 2.1%, P < 0.01; fundus CM 16.7% ± 2.2%, P < 0.01; gastric body LM 16.8% ± 2.3%, P < 0.01; body CM 12.7% ± 2.6%, P <0.01; antrum LM 12.3% ± 1.3%, P < 0.01; antrum CM 16.7% ± 4.5%, P < 0.01; pylous CM 12.7% ± 5.0%, P < 0.05);(2)contractile frequencies of body LM, both LM and CM of antrum and pylorus CM (5.1/min ± 0.2/min to 5.6/min ± 0.2/min, 5.9/min ± 0.2/min to 6.6/min ± 0.1/min, 5.4/min ± 0.3/min to 6.3/min ± 0.4/min, 1.3/min ± 0.2/min to 2.3/min ± 0.3/min, respectively, P < 0.05); the mean contractile amplitude of antral circular muscle (58.6% ± 18.4%, P < 0.05) and (3)the motility index of pylorus CM (145.0% ± 23.8%, P < 0.01), but decrease the mean contractile amplitude of gastric body and antral LM (-10.3% ± 3.3%, -10.5% ± 4.6%, respectively, P < 0.05 =. All the CCK-8 effects were not blocked by atropine or indomethacin. Secretin had no effect on gastric smooth muscle activity.CONCLUSION:CCK-8 possessed both excitatory and inhibitory action on contractile activity of different regions of stomach in guinea pigs. Its action was not mediated via cholinergic M receptor and endogenous prostaglandin receptor.

Effects of Dangshen on isolated gastric muscle strips in rats.

AIM:To study the effects of Dangshen dried root of Codonopsis Pilosula (Franch) Nannf on contractile activity of isolated gastric muscle strips in rats and its possible mechanism involved.METHODS:Each isolated gastric muscle strip was put in a tissue chamber containing 5ml Krebs solution, constantly warmed by water jacket at 37?mgr; and supplied with a mixed gas of 95% O(2) and 5% CO(2). After incubating for 1h with 1g tension, Dangshen of varied concentration was added cumulatively in the tissue chamber at intervals of 2 minutes. The isometrical response was measured on ink-writing recorders.RESULTS:Dangshen dose dependence increased the resting tension of longitudinal muscle (LM) of fundus (r =0.96, P < 0.01), the mean contractile amplitude of circular muscle (CM) of the stomach body (r =0.87, P < 0.05) and CM of antrum (r =0.98, P < 0.01), and the motility index CM of pylorus(r =0.87, P < 0.05). Atropine (5 10( 8)mol/L) or Hexamethonium (10( 5)mol/L) or Indomethacin (5 10( 7)mol/L) was given 2 minutes before the administration of Dangshen, it did not abolish its dose related manner. Atropine apparently reduced the increasing action of 10% and 30% Dangshen on the resting tesion of LM of fundus (P < 0.05), 30%, 100% and 200% Dangshen on bodied strips (P < 0.05), 100% and 200% Dangshen on antral strips (P < 0.05).Hexamethonium reduced the increasing action of 10% and 30% Dangshen on the resting tesion of LM of fundus (P < 0.05 and P < 0.05), 30%, 100% and 200% Dangshen on bodied strips (P < 0.05), and 100% and 200% Dangshen on pyloric strips (P < 0.05). Indomethacin inhibited the effect of 10% Dangshen on the resting tesion of LM of fundus (P < 0.05), but did not affect the exciting action of Dangshen on strips of body, antrum and pylorus.CONCLUSION:The results showed that Dangshen possessed exciting action on the isolated gastric smooth muscle strips of the rat.The exciting action of Dangshen was partially mediated via cholinergic M and N receptors.