Effects of Beta 2 adrenergic agonist [terbutaline], in dogs with acute hyperkalemia

ABSTRACT

This work was carried out to study the effects of gradually increasing doses of terbutaline [B2 agonist] on canine model of acute hyperkalemia to evaluate the possible use of B2 agonists in the management of acute hyperkalemia. The latter was induced by IV. infusion of Kcl during the whole period of the experiment, 4 hours. Potassium chloride infusion leads to a gradual increase in plasma K+ and no significant change in plasma glucose or arterial Bp. Hyperkalemic ECG changes depend on plasma K+ level ending in marked widening of QRS and large undulated pattern and lastly asystole. Administration of terbutaline IV in gradually increasing doses, and increasing by the same for 5 doses, resulted in dose related decrease of plasma K+ and increase in glucose levels. Also, terbutaline converted ECG changes induced by Kcl loading to sinus rhythm and prevented the ECG changes resulting from continuous Kcl infusion. The effect of terbutaline is mediated through stimulation of B2 receptors, since it is blocked by non selective blockade B1 and B2 [propranolol] and not by selective B1 blockade [atenolol]. So, correction of hyperkalemic ECG changes following terbutaline is a result of a decreased plasma K+ level, which is blocked by propranolol and is not affected by atenolol