Abstract
Effects of flow rate changes on nitric oxide (NO)formation in vascular endothelial cells were investigated in isolated canine mesenteric arterial bed preparations. Stepwise increases in the flow rate from 8 ml/min to 40 ml/min significantly (P <0.05)elevated perfusion pressure in a rate-dependent manner. In the presence of NG-nitro-L-arginine (L-NNA, 100 μM), perfusion pressures were significantly (P<0.01)higher than those observed under control conditions at all flow rates examined. Sodium nitroprusside (SNP)(0.1-10 μM)counteracted the pressor effect of L-NNA in a concentration-dependent manner. Increases in the flow rate from 10 ml/min to 40 ml/min significantly (P < 0.05)augmented cyclic GMP production in the vascular bed preparation. The flow-induced cyclic GMP response was significantly (P<0.05)attenuated by L-NNA (100 μM). These results demonstrate that 1)the amount of NO released from endothelial cells toward vascular smooth muscle cells can be semi-quantified with SNP, and 2)an increase in the flow rate stimulates NO formation in endothelial cells of resistance arteries, which may play an important part in regulating systemic blood pressure.
