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Effects of Changes in pH and P CO2 on Wall Tension in Isolated Rat Intrapulmonary Arteries
Author(s) -
Sweeney Michele,
O'Regan Ronan G.,
McLoughlin Paul
Publication year - 1999
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1111/j.1469-445x.1999.01864.x
Subject(s) - hypercapnia , acidosis , pco2 , respiratory acidosis , chemistry , intracellular ph , medicine , vasodilation , anesthesia , cardiology , anatomy , extracellular , biochemistry
SUMMARY 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; P CO2 , 34.4 ± 0.5 mmHg) to hypercapnic acidosis (pH change, ‐0.24 ± 0.01; P CO2 change, +27.5 ± 0.9 mmHg), isohydric hypercapnia (pH change, ‐0.02 ± 0.01; P CO2 change, +28.5 ± 0.8 mmHg) and normocapnic acidosis (pH change, ‐0.24 ± 0.01; P CO2 change, ‐0.5 ± 0.3). Arteries were submaximally preconstricted with prostaglandin F 2alpha; and changes in tension are expressed as a percentage of the 80 mM KCl‐induced contraction (%P o ). Mean changes in wall tension on switching to hypercapnic acidosis (+4.4 ± 3.7%P o ), isohydric hypercapnia (+1.9 ± 2.2%P o ) and normocapnic acidosis (−1.5 ± 1.9%P o ) were not significantly different from the change observed on switching to control conditions (+3.5 ± 1.1%P o ), and were unaltered by endothelial removal. In isolated carotid preparations, the change in tension in isohydric hypercapnia (‐6.8 ± 7.1%P o ) was not significantly different from that observed in control switches (+8.6 ± 3.2%P o ). Significant reductions in tension ( P < 0.001) were observed in hypercapnic (‐42.9 ± 7.8%P o ) and normocapnic acidosis (‐36.4 ± 9.0%P o ). These data suggest that intrapulmonary arteries are resistant to the vasodilator effects of extracellular acidosis observed in systemic (carotid) vessels.