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

TitleEffect of pH on ionic exchange and function in rat and rabbit myocardium.
Publication TypeJournal Article
Year of Publication1975
AuthorsPoole-Wilson PA, Langer GA
JournalAm J Physiol
Date Published1975 Sep
KeywordsAcidosis, Acidosis, Respiratory, Alkalosis, Respiratory, Animals, Epinephrine, Heart, Hydrogen-Ion Concentration, In Vitro Techniques, Ion Exchange, Male, Myocardium, Perfusion, Potassium, Propranolol, Rabbits, Rats, Sodium

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+.

Alternate JournalAm J Physiol
PubMed ID2014
Grant List091038 / / Wellcome Trust / United Kingdom
100591 / / Wellcome Trust / United Kingdom
095938 / / Wellcome Trust / United Kingdom
100544 / / Wellcome Trust / United Kingdom
090441 / / Wellcome Trust / United Kingdom
097903 / / Wellcome Trust / United Kingdom
097170 / / Wellcome Trust / United Kingdom
100406 / / Wellcome Trust / United Kingdom
100921 / / Wellcome Trust / United Kingdom
095495 / / Wellcome Trust / United Kingdom
084655 / / Wellcome Trust / United Kingdom
101234 / / Wellcome Trust / United Kingdom

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