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[Study on vasorelaxations of oxyphenamone and its mechanism]
1Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100005, China.
Aim:
To study the vasorelaxation action of oxyphenamone (Oxy) and its mechanism.
Methods:
The contractile response of isolated rabbit renal, femoral and mesentery artery preparations was determined.
Results:
Oxy was shown to inhibit the contractile force of renal, femoral and mesentery arteries induced by phenylephrine in a concentration dependent manner. The vasorelaxation produced by Oxy was not attenuated by removal of the endothelium. Oxy (10(-6)-10(-4) mol.L-1) relaxed the contractions induced by KCl 30 mmol.L-1 as well as KCl 80 mmol.L-1, but the contraction curve of KCl 80 mmol.L-1 was shifted significantly to the right. Oxy in lower concentration (10(-6) and 5 x 10(-6) mol.L-1) increased the contractions induced by Ang II, and in middle concentration (10(-5) mol.L-1) it did not affect the contractions induced by Ang II. Whereas in higher concentration (5 x 10(-5) mol.L-1) it obviously inhibited the contractions induced by Ang II.
Conclusion:
Oxy showed significant vasorelaxation to various vascular preparations, and its vasorelaxation action is endothelium independent. The mechanism of its vasorelaxations seems to be related with Ca2+ activated K+ channel (Kca channel) and Ca2+ channel in vascular smooth muscle cells but its true mechanism needs further study.