Some physiological reactions stimulated by isadrine in experimental hyperthyroidism in rats

Abstract

The chronotropic, calorigenic, and thermogenic effects of isopropyl noradrenalin (INA) and of the vapor mixture of INA and propranolol were studied in 86 adult male albino rats over the course of development of hyperthyrosis induced by 1 to 12 injections of triiodothyronin in a dose of 100 \xg/kg. The Pl-adrenergic reaction of the heart and the calorigenic and thermogenic reactions undergo several phases upon stimulation with isadrin in a dose of 2.0 pg/kg/min: latent period, period of high reactivity, and period of reduction of this activity. The efficacy of inderal (25 \ig/kg/min) adrenoblocking of the positive chronotropic effect of exogenously administered isadrin decreases with the progress of hyperthyrosis.