Abstract
Pitressin is an intense coronary constrictor capable, upon intracoronary injection, of causing sufficient constriction and reduction of coronary flow to depress the contractile effort of the myocardium.
Epinephrine is not a coronary constrictor in the dog. On the other hand, while the coronary flow increases after injection of the drug, this increase with the pure alkaloid is not much greater than would be anticipated from the rise of aortic pressure and follows by an interval of many seconds the appearance of myocardial stimulation induced by the drug. It is concluded therefore that epineprhine has only a weak coronary dilating effect per se, and that the apparently prominent coronary dilator action observed, particularly with the 1:1000 solution, is due in large part to a marked increase of myocardial metabolic activity, out of proportion to the increased cardiac work, to a coronary dilator effect of the preservative, and to a relative increase in the total diastolic time per minute due to shortening of the S/C ratio.
Angina following epinephrine injection is probably due to failure of the drug to induce directly sufficient coronary dilation and increased blood flow, to supply the augmented myocardial metabolism, resulting in a relative myocardial ischemia.
Footnotes
- Received August 31, 1942.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|