Interaction between calcium and hydrogen ionsin canine coronary arteries

G. J. Rinaldi, E. Amado Cattaneo, H. E. Cingolani

Research output: Contribution to journalArticle


In vitro experiments were carried out to study the effects of "respiratory" and "metabolic" acid-base alterations on canine coronary arteries precontracted by high potassium. Alkalosis (pH 7.70±0.02) increased the coronary tone by 33±3% (P2 or in bicarbonate concentration. The contractile changes were not abolished neither by alpha or beta adrenergic blockade nor by endothelium denudation. The effect of pH could not be offset by altering extracellular potassium or calcium when the plteau of the relationship between contractility of the smooth muscle and concentration of these ions was reached. When tonus developed by the strips and [Ca2+]0 were plotted reciprocally, DTmax significantly increased in alkalosis and decreased in acidosis. No significant changes in Ca50 ([Ca2+]0 necessary to obtain 50% of maximal force) were detected. pH changes did not modify Ca2+ influx but a relaxation of similar extent induced by nifedipine produced a detectable decrease in Ca2+ influx. Ca2+ efflux was, augmented in acidosis and depressed in alkalosis. Our data do not support the hypothesis of hydrogen ion changes inducing calcium influx alterations in acompetitive fashion as the mechanism involved to contract or relax conduit coronary arteries. On the contrary, they suggest that acid-base variations alter the contractile activity of vascular smooth muscle by modulating Ca2+ efflux.

Original languageEnglish (US)
Pages (from-to)773-784
Number of pages12
JournalJournal of Molecular and Cellular Cardiology
Issue number8
Publication statusPublished - 1987
Externally publishedYes



  • Calcium and coronary arteries
  • pH and coronary arteries
  • Vasospastic angina

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Cite this