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.

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.

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.