THE RELATIONSHIPS BETWEEN ELECTRICAL AND MECHANICAL EVENTS IN RABBIT AORTIC STRIPS

¹ Department of Pharmacology, University of Mississippi Medical Center,Jackson, Mississippi

This study was undertaken in an attempt to measure electrical changes and mechanical response in the rabbit aortic strip and to gain some insight into the relationship between mechanical and electrical events in a large mammalian blood vessel. An external electrode technique was used to measure potential changes. Simultaneous tension changes were recorded by means of a strain gauge transducer. It was found that isotonic potassium chloride Ringer's solution produced membrane depolarization of 9.6 ± 0.5 mV followed by contraction and an artifacual (junctional) potential of 1.9 ± 02 mV. Epinephrine (1 µg/ml) produced an immediate contraction followed by membrane hyperpolarization of 8.6 ± 1.0 mV. Angiotensin produced immediate contraction but no potential changes. Ca-free Ringer's solution produced depolarization and either no tension changes or relaxation. It was concluded that mechanical events may occur independently of changes in the resting membrane potential in the rabbit aortic strip.