Effects of extracellular pH on the response of the isolated rat mesenteric artery to electrical field stimulation.
In experiments on isolated segments of the rat mesenteric artery, effects of changes in solution pH on the response of the segments to noradrenaline (10 microM) or electrical field stimulation (EFS) were studied. The pH 7.8 solution slightly increased (from 0.48 +/- 0.07 mN at pH 7.4 to 0.67 +/- 0.12 mN or by 41%). while the pH 7.0 and 6.6 solutions significantly decreased (to 0.16 +/- 0.05 and 0.08 +/- 0.04 mN or by 66 and 83%, respectively) the EFS-evoked response of the vessel prestretched to the value corresponding to the intravascular pressure of about 100 mm Hg. A pH shift either to the alkaline or acidic range did not change the resting tension (15.65 +/- 0.74 mN at pH 7.4) of the vessel without precontraction. The pH 6.6 solution reduced the response to noradrenaline twofold. Dilation produced by EFS of noradrenaline-precontracted segment was inhibited and the constrictor responses appeared in the pH 6.6 solution. In the vessel pretreated with N(G)-nitro-L-arginine (100 microM), the acidification of the solution (pH 6.6) inhibited the response of the vascular segment to EFS to a lower extent and did not change its response to noradrenaline. The data obtained demonstrate an inhibitory effect of acidosis on reactivity of the rat mesenteric artery as well as a modification of this effect under a high initial tone of the vessel studied.
Dvoretsky
D P
DP
Laboratory of Circulation, Pavlov Institute of Physiology, St. Petersburg, Russia. yartsev@infran.ru
Karachentseva
O V
OV
Yartsev
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VN
D000138:Acidosis / Q000503:physiopathology; D000818:Animals; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009129:Muscle Tonus / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052250:Nitric Oxide Synthase Type III; D019335:Nitroarginine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D019335:Nitroarginine; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D009638:Norepinephrine