SOME DRUG EFFECTS ON CALCIUM MOVEMENTS IN AORTIC STRIPS

¹ Department of Pharmacology, Medical College of Virginia, Richmond, Virginia

Norepinephrine, histamine and potassium are known to interact with calcium in the induction of contraction in vascular smooth muscle. The importance of divalent cations in the induction of contraction has been investigated in the present study. Replacement of calcium with strontium was more effective in supporting drug- induced tension development than was replacement of calcium with barium. The response to potassium was nearly the same in the presence of strontium or calcium in the bathing solution. Tracer studies with Ca⁴⁵ have been done to attempt to establish some drug-calcium interactions. It has previously been demonstrated that a portion of the Ca⁴⁵ taken up by aortic strips is lost very slowly in the absence of exchangeable, nonradioactive divalent cation (Hudgins and Weiss, 1969). Utilizing similar experimental conditions, it has been possible to demonstrate drug-induced release of Ca⁴⁵ from this tissue. The antagonists, phentolamine and procaine, were used to attempt to alter Ca⁴⁵ release by norepinephrine and histamine.

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				A. V. Somlyo and A. P. Somlyo Strontium Accumulation by Sarcoplasmic Reticulum and Mitochondria in Vascular Smooth Muscle Science, November 26, 1971; 174(4012): 955 - 958. [Abstract] [PDF]