ABSTRACT
Aim To investigate the role of calcium-independent phospholipase A2(iPLA2)in calcium regu-lation of intrarenal artery smooth muscle contraction.Methods The method of measuring the tension of isolated arterioles was used to explore the effect of bromoenol lactone(BEL), a specific inhibitor of iPLA2, on the tension of the intrarenal arteries in mice induced by different calcium channels, and the laser confocal calcium measurement technology was used to investigate the effect of BEL on the intracellular calcium influx mediated by arachidonic acid-mediated calcium channels.Results The intrarenal artery concentration dependent contractile response induced by the vasoconstrictors phenylephrine and 5-hydroxy tryptamine was inhibited by BEL(P<0.01).The contraction curve induced by CaCl2 was also inhibited by BEL(P<0.05).In the calcium-free K-H solution incubated with nifedipine, the intrarenal artery vasoconstriction caused by the release of sarcoplasmic reticulum calcium and the calcium influx of the SOC channel induced by CaCl2 was inhibited by BEL(P<0.05).BEL significantly inhibited the external calcium influx mediated by the ARC channel of human aortic smooth muscle cell lines incubated with nifedipine(P<0.01).Conclusions iPLA2 mediates the contractile response of intrarenal arteries by regulating the functions of L-type calcium channels, sarcoplasmic reticulum calcium release, SOC channels and ARC channels.
ABSTRACT
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.