Abstract
Purpose : Anabolic steroids and β2-agonists are known to induce muscle hypertrophy. Few reports, however, exist concerning the physiological effects of over dosage. Therefore, acute effects of β2-agonist, clenbuterol (CLE) on plasma volume ratio (PVR : index of extracellular fluid volume), and plasma glucose, triglyceride and total cholesterol, insulin and cyclic AMP levels in rats were studied. Methods : Male SD rats (n = 48) were used. Two experiments were carried out : 1) the dose (0.01, 0.05 and 0.5 mg/kg BW)-response effects of CLE on plasma energy substrate and PVR levels, and 2) the acute effect of CLE (1.0 mg/kg BW) on plasma insulin and cyclic AMP levels. 0.9% NaCl solution was administered to the control rats. Plasma energy substrates were assayed by the routine methods. Plasma insulin and cyclic AMP were assayed by ELISA. Results : CLE increased significantly plasma glucose, triglyceride and total cholesterol according to the dose-dependent manner. PVR also increased with the increase of CLE dose, suggesting the increase of the dose-dependent extracellular fluid volume. CLE increased the plasma insulin concentration to 8.1 times, in 1 hours after administration, compared with the control. However, plasma cyclic AMP levels showed no significant changes. Conclusion : CLE increased dose-dependently rat plasma energy substrate level and PVR. Further, CLE increased plasma insulin levels without changing plasma cyclic AMP. [Jpn J Physiol 54 Suppl:S234 (2004)]
