Influence of aldosterone on isometric tension development in the rat heart

¹ Department of Physiology, Boston University School of Medicine, Boston, Massachusetts

Isometric twitch curves were recorded from preparations of rat heart trabeculae carneae removed from normal or adrenalectomized animals, or from normal animals injected for 3 days with saline or with 3 µg/day of d-aldosterone. Preparations from normal and from adrenalectomized animals were stimulated for 60 min in aldosterone-free Ringer's solution, or for 30 min in aldosterone-free Ringer's followed by 30 min in Ringer's containing 3 x 10^–4 µg/ml of d-aldosterone. For a number of preparations from adrenalectomized animals the concentration of aldosterone was increased to 3 x 10^–1 µg/ml. Regardless of treatment, all preparations were stimulated for a total of 1 hr at a rate of approximately 395/min; subsequently the recorded twitch curves were analyzed for peak tension development and for tension-time area. Although adrenalectomy tended to lower these variables of in vitro heart muscle performance, aldosterone, either administered in vivo or added directly to the isolated muscle bath, was without influence. It is concluded that aldosterone in the concentrations used does not alter the isometric tension characteristics of isolated rat heart muscle.

Note:
With the Technical Assistance of Edith I. McKeever