Calcium Content and Force of Drug-Induced Contractions of Arterial Muscle During Recovery in vitro 1

Abstract

Summary and Conclusions

Studies were designed, using rabbit aortic strips, to investigate the possible role calcium (Ca²⁺) ions play in the recovery of depressed, drug-induced contractions of excised, isolated blood vessels. The present experiments demonstrated that: (i) excision of aorta from intact rabbits and the subsequent surgical preparation and incubation of helical strips, at physiologic temperature in vitro, severely impairs the development of full sensitivity, of these aortic smooth muscle cells, to a variety of vasoactive substances for a period of 3 hr. (ii) A close relationship was found to exist between the ability or inability of different vasoactive drugs (e.g., epinephrine, histamine, potassium, and barium) to induce a maximal contractile response and the total Ca²⁺ content (as quantitatively determined by atomic absorption spectrophotometry). And (iii) mechanical (surgical) injury may alter the in vivo Ca²⁺ content of arterial smooth muscle.