AHEART April 47/4

Nakano, Toshihide, Ryuji Tominaga, Ichiro Nagano, Hayato Okabe, and Hisataka Yasui. Pulsatile flow enhances endothelium-derived nitric oxide release in the peripheral vasculature. Am J Physiol Heart Circ Physiol 278: H1098–H1104, 2000.—The effects of pulsatility in blood flow on endothelium-derived nitric oxide (EDNO) release in the peripheral vasculature were investigated. The basal and flow-stimulated EDNO release were compared between pulsatile and nonpulsatile systemic flows before and after the administration of NO synthase inhibitor NG-monomethyl-Larginine (L-NMMA). Peripheral vascular resistance (PVR) was significantly lower in pulsatile flow than in nonpulsatile flow, but this difference disappeared after L-NMMA. The percent increase in PVR by L-NMMA was significantly larger in pulsatile flow. In reactive hyperemia in the hindlimb, the peak flow did not differ; however, both the repayment flow and the duration were significantly larger in pulsatile flow. Percent changes of these parameters by L-NMMA were significantly larger in pulsatile flow. These data indicated that pulsatility significantly enhances the basal and flowstimulated EDNO release in the peripheral vasculature under in vivo conditions. We also studied the involvement of the Ca21-dependent and Ca21-independent pathways in flowinduced vasodilation using calmodulin inhibitor calmidazolium and tyrosine kinase inhibitor erbstatin A. PVR was significantly elevated by erbstatin A but not by calmidazolium, suggesting that flow-induced vasodilation was largely caused by tyrosine kinase inhibitor-sensitive activation of NO synthase.