Practolol inhibition of some salbutamol-induced metabolic and hormonal responses.

The effect of practolol (a selective beta1-adrenergic receptor blocking agent) on increased blood insulin, sugar, lactate and FFA and decreased blood phosphorus and potassium induced by salbutamol (a primarily beta2-adrenergic stimulant) was studied in 6 normal volunteers. Practolol abolished the rise of lactate and glucose, suggesting that changes in these parameters due to salbutamol are mediated by beta1-receptors. The rise of insulin and the fall of potassium were only partially inhibited, and the possible involvement of the beta2-receptors as well in these 2 cases cannot be ruled out. The decrease of phosphorus and the FFA rise were not affected and thus appear to be primarily dependent on beta2-receptors.