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Effect of pH on ionic exchange and function in rat and rabbit myocardium

zqyin 添加于 2014-9-14 09:01 | 1106 次阅读 | 0 个评论

作者
Poole-Wilson PA, Langer GA
摘要
The effects of pH variation on ionic exchange and mechanical function were studied in the arterially perfused rat and rabbit septa. The pH and PCO2 of the control perfusate were 7.40 and 39 mmHg, respectively. In the rabbit septum a metabolic acidosis (pH equals 6.82, PCO2 equals 39 mmHg) caused a loss of 16% of control tension in 12 min. Na+ and K+ exchange were unaltered. A comparable respiratory acidosis (pH equals 6.81, PCO2 equals 159 mmHg) caused a 51% loss of tension in 2 min. Na+ exchange was unaltered but K+ efflux fell from 8.9 +/- 0.6 (mean +/- SE) to 4.9 +/- 0.3 mmol/kg dry wt per min (P less than 0.001, n equals 10). A net gain of K+ of 16.9 +/- 1.7 (n equals 14) mmol/kg dry wt occurred and was attributable to a delayed fall in K+ influx relative to efflux over 15 min. The net gain could not be mimicked by epinephrine administration or blocked by propranolol and was absent in the beating rat septum and the quiescent rabbit septum. These results suggest that the net uptake of K+, which appears to be dependent on a period of depolarization, and the changes of contractility are controlled by the H+ ion concentration at a cellular site whose exchange with the extracellular space is characterized by a considerable restriction of diffusion. Changes of contractility are not related to the net uptake of K+.
详细资料
- 关键词: Acidosis/chemically induced/*metabolism; Acidosis, Respiratory/chemically induced/*metabolism; Alkalosis, Respiratory/chemically induced/*metabolism; Animals; Epinephrine/pharmacology; Heart/drug effects; Hydrogen-Ion Concentration; Ion Exchange; Male; Myocardium/*metabolism; Perfusion; Potassium/metabolism; Propranolol/pharmacology; Rabbits; Rats; Sodium/metabolism
- 文献种类: Journal Article
- 期刊名称: The American Journal of Physiology
- 期刊缩写: Am J Physiol
- 期卷页: 1975年第229卷第3期 570-581页
- ISBN: 0002-9513
学科领域自然科学 » 物理学
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