Plasma insulin levels and ?-adrenoceptor antagonists

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Abstract
The effect of β-adrenoceptor antagonists on the intravenous glucose tolerance test was investigated in conscious dogs. dl-Celiprolol (cardioselective with ISA=intrinsic sympathomimetic activity) 200 and 1000 μg/kg i.v., dl-metoprolol (cardio-selective without ISA) 200 and 1000 μg/kg i.v., dl-pindolol (non-selective with ISA) 5 and 25 μg i.v. and l-bupranolol (non-selective without ISA) 10 and 50 μg/kg i.v. were used in the study. The influence of β-adrenoceptor antagonists on the plasma glucose and immunoreactive insulin following the intravenous glucose tolerance test were evaluated by calculating the respective areas under the plasma curve. The present investigtion clearly demonstrates the marked difference between the various β-adrenoceptor antagonists on heart rate and, especially on metabolic parameters. dl-Metoprolol, a β-adrenoceptor antagonist with cardioselectivity and without ISA can be assumed not to alter plasma insulin level and glucose assimilation. l-Bupranolol, a non-selective β-adrenoceptor antagonist without ISA reduces plasma insulin level and probably enhances peripheral glucose uptake, resulting in an “unchanged” glucose tolerance. dl-Celiprolol or dl-pindolol, β-adrenoceptor antagonists with ISA, but cardioselective or non-selective enhance both, basal insulin level and insulin level after glucose stimulation but must be assumed to decrease peripheral glucose uptake since here too glucose tolerance was unchanged.