Effects of changes in pH and PCO2 on wall tension in isolated rat intrapulmonary arteries.
We examined mean ( S.E.M.) changes in wall tension in isolated rat intrapulmonary arteries on switching from control conditions (pH 7.38 +/- 0.01; PCO2, 34.4 +/- 0.5 mmHg) to hypercapnic acidosis (pH change, -0.24 +/- 0.01; PCO2 change, +27.5 +/- 0.9 mmHg), isohydric hypercapnia (pH change, -0.02 +/- 0.01; PCO2 change, +28.5 +/- 0.8 mmHg) and normocapnic acidosis (pH change, -0.24 +/- 0.01; PCO2 change, -0.5 +/- 0.3). Arteries were submaximally preconstricted with prostaglandin F2 and changes in tension are expressed as a percentage of the 80 mM KCl-induced contraction (%Po). Mean changes in wall tension on switching to hypercapnic acidosis (+4.4 +/- 3.7 %Po), isohydric hypercapnia (+1.9 +/- 2.2 %Po) and normocapnic acidosis (-1.5 +/- 1.9 %Po) were not significantly different from the change observed on switching to control conditions (+3.5 +/- 1.1 %Po), and were unaltered by endothelial removal. In isolated carotid preparations, the change in tension in isohydric hypercapnia (-6.8 +/- 7.1 %Po) was not significantly different from that observed in control switches (+8.6 +/- 3.2 %Po). Significant reductions in tension (P < 0.001) were observed in hypercapnic (-42.9 +/- 7.8 %Po) and normocapnic acidosis (-36.4 +/- 9.0 %Po). These data suggest that intrapulmonary arteries are resistant to the vasodilator effects of extracellular acidosis observed in systemic (carotid) vessels.
Sweeney
M
M
Department of Human Anatomy and Physiology, University College, Earlsfort Terrace, Dublin 2, Ireland.
O'Regan
R G
RG
McLoughlin
P
P
D000138:Acidosis / Q000503:physiopathology; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism*; D002339:Carotid Arteries / Q000502:physiology; D015237:Dinoprost / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
D002245:Carbon Dioxide; D010656:Phenylephrine; D015237:Dinoprost