Involvement of NO and EDHF in flow-induced vasodilation in isolated hamster cremasteric arterioles.
Flow-induced vasodilation in hamster cremasteric arterioles was investigated with special reference to the roles of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF). Arterioles (approximately 60 microm resting diameter) were cannulated, and suffused with MOPS solution at 37 degrees C (mean intraluminal pressure: 80 cm H(2)O). Step increases in the perfusate flow elicited a dose-dependent vasodilation, which was almost proportional to the increases in calculated wall shear stress (WSS). N(omega)-nitro L-arginine methyl ester (L-NAME, 100 microM) reduced the flow-induced vasodilation by approximately 50%, whereas indomethacin (10 microM) produced no significant effect. In the presence of L-NAME, the residual vasodilation was eliminated by treatment with the cytochrome P-450 monooxygenase inhibitor 17-octadecynoic acid (17-ODYA, 50 microM), sulfaphenazol (10 microM), tetraethylammonium (TEA, 3 mM; a nonselective Ca(2+)-activated K(+) channel inhibitor), or charybdotoxin (ChTX, 0.1 microM; intermediate or large conductance Ca(2+)-activated K(+) channel inhibitor). In the absence of L-NAME, the dilation was also reduced by approximately 50% by treatment with 17-ODYA, TEA, or ChTX. The residual vasodilation was eliminated by additional treatment with L-NAME. The inhibitor of ATP-sensitive K(+) channels (K(ATP)), glibenclamide, also caused a significant, but partial, reduction of the flow-induced vasodilation. The residual vasodilation was completely reduced by additional treatment with 17-ODYA, but not L-NAME. These findings suggest that in hamster cremaster, higher flow rate produces NO, K(ATP), and EDHF vasodilation of the arterioles under physiological conditions.
Watanabe
Sachiko
S
Department of Physiology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
Yashiro
Yasuaki
Y
Mizuno
Risuke
R
Ohhashi
Toshio
T
D000009:Abdominal Muscles / Q000098:blood supply*; D000818:Animals; D001160:Arterioles / Q000502:physiology; D001685:Biological Factors / Q000502:physiology*; D006224:Cricetinae; D066298:In Vitro Techniques; D008297:Male; D008647:Mesocricetus; D009569:Nitric Oxide / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
D001685:Biological Factors; C067410:endothelium-dependent hyperpolarization factor; D009569:Nitric Oxide