In vitro fertilization with frozen embryo transfer increased histamine-mediated contractile sensitivity via PKCß in human umbilical vein.

OBJECTIVE: In vitro fertilization-embryo transfer (IVF-ET) technologies (especially frozen ET) have been widely used, which might affect maternal and fetal health. Information regarding influence of IVF-ET on the vasoconstriction of human umbilical vein (HUV) is limited. This study determined effects of frozen ET on histamine-mediated vascular responses in HUV and related mechanisms. METHODS AND RESULTS: HUVs were collected from frozen ET conceived pregnancy and spontaneously conceived pregnancy (control). Histamine concentration in umbilical plasma was higher in frozen ET group than the control. Histamine-mediated contractile response curve was left-shifted in the frozen ET group when comparing with the control. In isolated HUV rings, H1R showed a critical role in regulating vascular constriction, while H2R played little roles in regulating vessel tone. Iberiotoxin and 4-aminopyridine didn't significantly change histamine-mediated constriction in HUVs. Histamine-induced vasoconstrictions were significantly decreased by nifedipine, KN93, or GF109203X, while the inhibitory effects were significantly greater in the frozen ET group in comparison to the control. The constrictions by Bay K8644, phenylephrine, or PDBu were stronger in frozen ET, respectively. There was a decrease in the protein expressions of H1R and H2R, an increase in protein expressions of BKCaα and PKCß. CONCLUSIONS: Histamine-induced constriction in HUV was mainly via H1R. The increased sensitivity to histamine in HUV following frozen ET cycles were linked to the enhanced PKCß protein expression and function. The new data and findings in this study provide important insight into influences of frozen ET on fetal vessel development and potential influence in long-term.

Opposing responses of the rat pulmonary artery and vein to phenylephrine and other agents in vitro.

BACKGROUND: Different from current cognition, our study demonstrated that adrenergic receptors agonist phenylephrine significantly relaxed isolated pulmonary artery but constricted pulmonary veins. Through comparing differences in the effects of commonly used vasoactive drugs on pulmonary artery and veins, the study aimed to improve efficiency and accuracy of isolated pulmonary vascular experiments, and to provide experimental basis for clinical drug use. METHODS: The contractile responses of pulmonary arteries and veins from twelve-week-old Male Sprague-Dawley rats to phenylephrine, arginine vasopressin (AVP), U46619, endothelin-1, and potassium chloride (KCl) were recorded, as well as the relaxation in response to phenylephrine, AVP, acetylcholine. To further explore the mechanism, some vessels was also pre-incubated with adrenergic receptors antagonists propranolol, prazosin and nitric oxide synthesis inhibitor N[gamma]-nitro-L-arginine methyl ester (L-NAME) before addition of the experimental drugs. RESULTS: Phenylephrine constricted pulmonary veins directly, but constricted pulmonary artery only after incubation with propranolol or/and L-NAME. The pulmonary artery exhibited significant relaxation to AVP with or without L-NAME incubation. AVP more clearly constricted the veins after incubation with L-NAME. Changes in vascular tension also varied from pulmonary artery to veins for KCl stimulation. Different from phenomena presented in veins, acetylcholine did not relax pulmonary artery preconstricted by KCl, U46619, and endothelin-1. CONCLUSIONS: According to the results, phenylephrine, KCl, AVP, and acetylcholine could be used to distinguish pulmonary arteries and pulmonary veins in vitro. This also suggested that the pulmonary arteries and pulmonary veins have great differences in physiology and drug reactivity.

Angiotensin-(1-7) induced vascular relaxation in spontaneously hypertensive rats.

Enhanced vasoconstriction and decreased vasodilatation due to endothelial dysfunction contribute to the progression of hypertension. Angiotensin (Ang)-(1-7) plays important roles in regulating the cardiovascular activity. The current study aimed to investigate the roles of Ang-(1-7) in modulating blood pressure, vascular tension and its signal pathway in spontaneously hypertensive rats (SHR). The effects of intravenous injection of drugs were determined in rats with anesthesia in vivo. Mesenteric artery (MA), coronary artery (CA) and pulmonary artery (PA) were isolated from rats and isometric tension measurements in arteries were performed. Compared with Wistar-Kyoto rats (WKY), the high K+ induced vasoconstriction was enhanced and acetylcholine-induced vasodilatation were attenuated in the MA, CA and PA in SHR. Intravenous injection of Ang-(1-7) decreased, while A-779 increased mean arterial pressure and abolished the hypotensive effect of Ang-(1-7) in SHR. Ang-(1-7) caused dose-dependent relaxation in MA, CA and PA in SHR, which was inhibited by pretreatment with Mas receptor antagonist A-779, nitric oxide (NO) synthase inhibitor l-NAME, guanylate cyclase inhibitor ODQ and protein kinase G (PKG) inhibitor DT-2. The Mas receptor expression, NO, cGMP and PKG levels of the three above arteries of SHR were lower than that of WKY. Ang-(1-7) increased the NO, cGMP and PKG levels in arteries from SHR, which was blocked by A-779. Activation of the Mas receptor by Ang-(1-7) relaxes the MA, CA, and PA through the NO-cGMP-PKG pathway, which contributes to the decrease of arterial pressure in SHR.

The association between cerebrovascular reactivity and resting-state fMRI functional connectivity in healthy adults: The influence of basal carbon dioxide.

Although widely used in resting-state fMRI (fMRI) functional connectivity measurement (fcMRI), the BOLD signal is only an indirect measure of neuronal activity, and is inherently modulated by both neuronal activity and vascular physiology. For instance, cerebrovascular reactivity (CVR) varies widely across individuals irrespective of neuronal function, but the implications for fcMRI are currently unknown. This knowledge gap compromises our ability to correctly interpret fcMRI measurements. In this work, we investigate the relationship between CVR and resting fcMRI measurements in healthy young adults, in both the motor and the executive-control networks. We modulate CVR within each individual by subtly increasing and decreasing resting vascular tension through baseline end-tidal CO2 (PETCO2), and measure fcMRI during these hypercapnic, hypocapnic and normocapnic states. Furthermore, we assess the association between CVR and fcMRI within and across individuals. Within individuals, resting PETCO2 is found to significantly influence both CVR and resting fcMRI values. In addition, we find resting fcMRI to be significantly and positively associated with CVR across the group in both networks. This relationship is potentially mediated by concomitant alterations in BOLD signal fluctuation amplitude. This work clearly demonstrates and quantifies a major vascular modulator of resting fcMRI, one that is also subject and regional dependent. We suggest that individualized correction for CVR effects in fcMRI measurements is essential for fcMRI studies of healthy brains, and can be even more important in studying diseased brains.

Farnesoid X receptor regulates vasoreactivity via Angiotensin II type 2 receptor and the kallikrein-kinin system in vascular endothelial cells.

Vascular farnesoid X receptor (FXR) ligands have been shown previously to regulate vascular tension. This study investigated whether FXR activation regulates vasoreactivity via the angiotensin II (Ang II) type 2 receptor (AT2 R) and the kallikrein-kinin system in rat aortic vascular endothelial cells (RAECs). Protein abundances of Ang II type 1 receptor (AT1 R), AT2 R, bradykinin type 1/2 receptor (B1 R, B2 R), small heterodimer partner-1 (SHP-1) and the endothelial and inducible NO synthases (eNOS/iNOS) were analysed by Western blotting. Real-time quantitative polymerase chain reaction was performed to analyse expression of eNOS and iNOS mRNA. Kallikrein activity and bradykinin content were assayed using spectrophotometry and a bradykinin assay kit, respectively. Aortic vasoconstriction and vasodilation were also investigated following FXR activation in the presence or absence of AT2 R and B2 R blockade. It was found that the FXR agonists GW4064 and INT-747, in a dose-dependent manner, increased the protein abundance of AT2 R, B2 R and SHP-1 and decreased that of AT1 R. AT2 R blockade with PD123319 reversed effects of FXR agonists on kallikrein activity and levels of SHP-1, B2 R and bradykinin. Moreover, it was found that GW4064 and INT-747 upregulated expression of eNOS and enhanced NOS activity, which attenuated vasoconstriction and induced vasodilation, respectively. These effects were partially reversed by PD123319 and by B2 R blockade with HOE140. The current work suggests that FXR regulates vascular tension by controlling the eNOS-NO system via activation of a pathway mediated by AT2 R-B2 R pathway in RAECs.

Formaldehyde regulates vascular tensions through nitric oxide-cGMP signaling pathway and ion channels.

Formaldehyde (FA) has been linked to the detrimental cardiovascular effects. Here, we explored the effects and mechanisms of FA on rat aortas both in vivo and in vitro. The results presented that FA evidently lowered the blood pressures of rats. The expression levels of BKCa subunits α and ß1 and iNOS of the aortas were up-regulated by FA in vivo. However, FA markedly reduced the levels of Cav1.2 and Cav1.3, which are the subunits of L-Ca2+ channel. Furthermore, the contents of NO, cGMP and iNOS in the aortas were augmented by FA. To further confirm these findings, the mechanisms accredited to these effects were examined in vitro. The data showed that FA contracted the isolated aortic rings at low concentrations (<300 µM), while it relaxed the rings at high concentrations (>500 µM). The FA-induced vasoconstriction at low concentrations was blocked partly by an inhibitor of ACE. The relaxation caused by FA at high concentrations was attenuated by the inhibitors of NO-cGMP pathway, L-Ca2+ channel and BKCa channel, respectively. Similarly, the expression of iNOS was strongly enhanced by FA in vitro. The effects of FA on the aortic rings with endothelium were significantly greater than those on the rings without endothelium. Our results indicate that the vasoconstriction of FA at low concentrations might be partially pertinent to endothelin, and the FA-caused vasorelaxation at high concentrations is possibly associated with the NO-cGMP pathway, L-Ca2+ channel and BKCa channel. This study will improve our understanding of the pathogenic mechanisms for FA-related cardiovascular diseases.

Tannic acid activates the Kv7.4 and Kv7.3/7.5 K(+) channels expressed in HEK293 cells and reduces tension in the rat mesenteric arteries.

OBJECTIVES: This study investigated the effect of tannic acid (TA), a plant-derived hydrolyzable polyphenol, on Kv7.4 and Kv7.5 K(+) channels and rat mesenteric artery. METHODS: Whole-cell patch clamp experiments were used to record the Kv7.4 and Kv7.3/7.5 K(+) currents expressed in HEK293 cells; and the tension changes of mesenteric arteries isolated from rats were recorded using small vessel myography apparatus. KEY FINDINGS: Tannic acid increases the Kv7.4 and Kv7.3/7.5 K(+) currents in a concentration-dependent manner (median effective concentration (EC50 ) = 27.3 ± 3.6 µm and EC50 = 23.1 ± 3.9 µm, respectively). In addition, 30 µm TA shifts the G-V curve of Kv7.4 and Kv7.3/7.5 K(+) currents to the left by 14.18 and 25.24 mV, respectively, and prolongs the deactivation time constants by 184.44 and 154.77 ms, respectively. Moreover, TA relaxes the vascular tension of rat mesenteric arteries in a concentration-dependent manner (half inhibitory concentration (IC50 ) = 148.7 ± 13.4 µm). CONCLUSION: These results confirms the vasodilatory effects of TA on rat mesenteric artery and the activating effects on the Kv7.4 and Kv7.3/7.5 K(+) channels, which may be a mechanism to explain the vasodilatory effect and this mechanism can be used in the research of antihypertension.

M-currents (Kv7.2-7.3/KCNQ2-KCNQ3) Are Responsible for Dysfunctional Autonomic Control in Hypertensive Rats.

Autonomic dysfunctions play important roles in hypertension, heart failure and arrhythmia, often with a detrimental and fatal effect. The present study analyzed if these dysfunctions involved M-channels (members of the Kv7/KNCQ family) in spontaneously hypertensive rats (SHR). Cardiac output and heart rate (HR) were recorded by a flow probe on the ascending aorta in anesthetized SHR and normotensive rats (WKY), and blood pressure (BP) by a femoral artery catheter. Total peripheral vascular resistance (TPR) was calculated. XE-991 (Kv7.1-7.4-inhibitor) reduced resting HR in WKY but only after reserpine in SHR. XE-991 increased TPR and BP baseline in both strains. Retigabine (Kv7.2-7.5-opener) reduced HR, TPR and BP, also after reserpine. Depolarization induced by 3,4-diaminopyridine (3,4-DAP), a voltage-sensitive K+ channel (Kv) inhibitor, activated release of both acetylcholine and norepinephrine, thus activating an initial, cholinergic bradycardia in SHR, followed by sustained, norepinephrine-dependant tachycardia in both strains. XE-991 augmented the initial 3,4-DAP-induced bradycardia and eliminated the late tachycardia in SHR, but not in WKY. The increased bradycardia was eliminated by hexamethonium and methoctramine (M2muscarinic receptor antagonist) but not reserpine. Retigabine eliminated the increased bradycardia observed in reserpinized SHR. XE-991 also increased 3,4-DAP-stimulated catecholamine release, but not after hexamethonium or reserpine. CONCLUSIONS: M-currents hampered parasympathetic ganglion excitation and, through that, vagal control of HR, in SHR but not WKY. M-currents also opposed catecholamine release in SHR but not in WKY. M-currents represented a vasodilatory component in resting TPR-control, with no strain-related difference detected. Excessive M-currents may represent the underlying cause of autonomic dysfunctions in hypertension.

L-type calcium channel involved in heterogeneity of arterial constriction in different organs of rats / 中国药理学通报

Aim To study whether there was arterial heterogeneity and association with L-type calcium channel (LCC) in different parts of arteries in re-sponse to certain vasoconstrictor. Methods The aor-ta, renal arteries and coronary arteries were dissected from rats. Arterial ring contractions induced by pheny-lephrine (Phe), 5-hydroxyl tryptamine (5-HT) or U46619 in concentration-dependent manner were meas-ured using the Multi Myograph system and the response to nifedipne was observed. Results (1) Phe had no obvious effect on the tension of coronary artery,but in-duced concentration-dependent vasoconstriction in aor-ta and renal artery,and pEC50of aorta was significantly higher than that of renal artery (P<0.05). The inhi-bition rate of nifedipine on the aortic contractile re-sponses was significantly higher than that of renal arter-y (P<0.05). (2) The contraction induced by 5-HT on aorta was not obvious, but was significant on renal artery and coronary artery. The inhibitory rate of nife-dipine on coronary artery vasoconstriction was signifi-cantly higher than that of renal artery (P <0.05). (3) U46619 could induce aorta,renal artery and coro-nary artery concentration- dependent contraction, but the Emaxof them were both higher than that of renal ar-tery (P<0.05). And the pEC50of aorta was the lar-gest (P<0.05). Nifedipine significantly inhibited the contraction of aorta, renal artery and coronary artery induced by U46619 with the greatest inhibitory rate on the coronary artery vasoconstriction and minimal inhibi-tion on aortic vasoconstriction. Conclusions The re-sponse to certain vasoconstrictor is different among aor-ta, renal artery and coronary artery in rats, and the contraction mediated by L-type calcium channel is also different.

Direct Effects of Ketamine on Isolated Rat Aorta and Pulmonary Artery / 대한마취과학회지

The vasoactive effecs of ketamine on aortic and pulmonary arteries have not heen clearly characterized. Nevertheless, it has been recommended to avoid ketamine in systemic and pulmonary hypertension because of its tendency to increase systemic and pulmonary vascular resistance. This study was designed to investigate and compare the direct effects of ketamine on isolated rat aortic and pulmonary arteries, with or without intact endothelium. The optimal resting tension (Lmax) of each ring was searched hased on contractile responses to 3.7X10(6)M norepinephrine. Once the Lmax was Obtained, the peak developed tension was recorded as the control. Thereafter, in the second part of the experiments, prior to ketamine exposure, the endothelium was denuded which was confirmed pharmacologically using norepinephrine(3.7X10-6M) and acetylcholine(10(-6)M). In groups with intact endothelium, .3X10(3)M ketamine relaxed aortic and pulmonary artery ring by -10.3+/-5.6%, -17.8+/-4.4%, respectively. In groups without intact endothelium, 3X10(3)M ketamine relaxed aortic and pulmonary artery ring by -9.9+/-3.6%, -14.2+/-3.8%, respectively. It was statistically significant. In groups with or without intact endothelium, 0.1X10(3) M ketamine relaxed aortic and pulmonary artery ring. Hut it was statistically insignificant. We conclude that ketamine is a powerful aortic and pulmonary artery dilator in vitro and that is endothelium independent.

Effects of Thiopental Sodium, Midazolam, Propofol and Ketamine on Endothelial Nitric Oxide in Rat Thoracic Aortic Rings / 대한마취과학회지

BACKGROUND: Compared to inhalation and local anesthetics, little is known about the mechanisms of vascular effects of intravenous anesthetics. So we studied the effects of thiopental sodium, midazolam, propofol and ketamine on the endothelial nitric oxide-cGMP pathway and also on the membrane cyclooxygenase pathway. METHODS: After isolating ring strips of rat thoracic aorta, we measured the relaxation ED50 values of the four intravenous anesthetics from the maximally contracted using phenylephrine 10(-5)M. Then using L-NAME and methylene blue, we studied the effects of the drugs upon the NO-cGMP system. In addition, another pathway of vasodilation through membrane prostaglandin metabolism was examined using the membrane cyclooxygenase inhibitor, indomethacine. RESULTS: The following results were obtained. 1. Thiopental sodium (10(-5)M) did not have any effect on the PE induced contractions of aortic rings but midazolam (10(-6)M), propofol (10(-4)M) and ketamine (10(-3)M) significantly (P < 0.05) inhibited the PE induced contractions of aortic rings. 2. Midazolam 10(-6)M and propofol 10(-4)M induced relaxation of aortic rings were recovered with L-NAME pretreatment but ketamine induced relaxation was not recovered with L-NAME. 3. Midazolam 10(-6)M induced relaxation was not recovered with methylene blue pretreatment, but propofol 10(-4)M induced relaxation was recovered with methylene blue. 4. Indomethacine pretreatment induced further relaxation of midazolam or propofol induced relaxation of aortic rings. CONCLUSIONS: Midazolam, propofol and ketamine, but not thiopental sodium, relax rat thoracic aortic rings, and these relaxation effects of midazolam and propofol are endothelium dependent. Cyclooxygenase inhibition is related at least in part to midazolam or propofol induced relaxation, and guanylate cyclase to propofol induced relaxation.

Effects of resveratrol on isolated coronary artery rings of canine / 中国临床药理学与治疗学

AIM: To investigate the relaxative characteristics of resveratrol(RES) and 17?-Estradiol(EST) on coronary arteries in dogs and its mechanism.METHODS: Rings of canine coronary arteries were suspended in organ baths containing Krebs-Henseleit solution,and then isometric tension was measured.RESULTS: Both RES and EST caused the does-response contractile curve of KCl in K-H solution and CaCl_2 in Ca~(2+)-free K-H solution shift rightward,and their sensitivies and the values of maximum contractions had been decreased.In the N?-L-nitro-arginine,Methylene Blue and Sodium Orthovanadate groups,the vasorelaxant effects of both estrogens were markedly attenuated(P(0.05)).CONCLUSION: Resveratrol and 17?-Estradiol relaxe vascular smooth muscle in an endothelium-dependent manner,and are not related to KATP channel.