Effect of prostaglandins and nitric oxide on basal blood flow and acetylcholine-induced vasodilation in rat diaphragmatic microcirculation.
To assess the effect of prostaglandins and endothelium-derived relaxing factor (EDRF) on diaphragmatic microcirculation under basal conditions and after acetylcholine (ACh) stimulation, we studied a diaphragmatic preparation in anesthetized rats. With bicarbonate-buffered Ringer's solution suffusing the abdominal surface of the left costal diaphragm, laser-Doppler flowmetry was used to record microvascular blood flow (QLDF). Microvascular conductance (CLDF) was derived from QLDF by dividing by the systemic blood pressure. Drugs were applied to the surface of the diaphragm. Four series of experiments were performed. In Series 1 (n = 9), ACh (3 x 10(-5)-10(-3) mol/L) elicited a concentration-dependent increase in QLDF and CLDF. In Series 2 (n = 11), ACh-induced QLDF and CLDF changes were significantly attenuated after 30 minutes suffusion of indomethacin (10(-5) mol/L), although baseline QLDF and CLDF were little affected. In Series 3 (n = 7), following suffusion of N omega-nitro-L-arginine methyl ester (L-NAME) (10(-4) mol/L) for 30 minutes, there was no change in baseline QLDF and CLDF. The ACh-induced QLDF change was abolished, while there was still a slight increase in CLDF (172 +/- 26%) at high concentrations of ACh (10(-3) mol/L). In Series 4 (n = 5), co-administration of indomethacin (10(-5) mol/L) and L-NAME (10(-4) mol/L) for 30 minutes did not completely prevent the increase in CLDF (143 +/- 13%) induced by high concentrations of ACh (10(-3) mol/L). The data suggest low basal activities of both vasodilatory prostaglandins and EDRF in diaphragmatic microvascular beds of the anesthetized rat, while both mediators independently modulate microvascular responses to ACh.(ABSTRACT TRUNCATED AT 250 WORDS)
Chang
H Y
HY
Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan, ROC.
Chen
C W
CW
Hsiue
T R
TR
Chen
C R
CR
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D011453:Prostaglandins / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects*
D011453:Prostaglandins; D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester