A transient dilatation of pressurised rat cerebral arteries during rapid pressure increases is mediated by nitric oxide.
In pressurised resistance arteries in vitro, rapid pressure increases cause a transient "peak" dilatation, followed by a myogenic constriction. The mechanism of transient dilatation was investigated in isolated rat cerebral arteries in vitro using pressure myography. The peak increased with the amplitude of the pressure step. A near-maximal dilatation to 118+/-1.6% (SEM, n=20) of the diameter at 30 mmHg was produced by pressure steps from 30 to 75 mmHg. Nomega-nitro-l-arginine methyl ester (L-NAME, 20 microM) depressed the peak at the onset of a 30 to 75 mmHg pressure step to 49.8+/-14% of the control (n=6; P=0.04). D-NAME (20 microM) had no significant effect (82.1+/-13%; n=4; P=0.13). L-Arginine (400 microM) enhanced the peak (164+/-17% of control; n=8; P=0.01). Oxadiazolol (4,3-a) quinoxalin-1-one (ODQ, 2 microM) depressed the peak to 33.2+/-12% of control (n=5; P=0.012). 6-Anilino-5, 8-quinolinedone (LY 83583, 10 microM) depressed the peak to 18.8+/-2. 9% of control (n=3; P=0.01). Removing the endothelium decreased the peak to 15.3+/-11% of control (n=3; P=0.04). In conclusion, in rat cerebral arteries, the initial dilatation at the onset of a rapid step increase in pressure is an active dilatation involving endothelial NO release.
Doughty
J M
JM
Department of Physiology, University of Bristol, University Walk, Bristol BS8 1TD, UK.
Langton
P D
PD
D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001794:Blood Pressure; D002536:Cerebral Arteries / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010069:Oxadiazoles / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013696:Temperature; D014664:Vasodilation
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D000634:Aminoquinolines; D004791:Enzyme Inhibitors; D010069:Oxadiazoles; D011810:Quinoxalines; D009569:Nitric Oxide; C041715:6-anilino-5,8-quinolinedione; D001120:Arginine; D019001:Nitric Oxide Synthase; D006162:Guanylate Cyclase; D019331:NG-Nitroarginine Methyl Ester