Postsynaptic α1-Blockade with Terazosin Does Not Modify Insulin Sensitivity in Nonobese Normotensive Subjects

Plasma insulin levels and the sensitivity of peripheral tissue to insulin (SI) have pathophysiological, therapeutic, and possibly also prognostic relevance. To investigate the effects of short-term selective alpha 1-adrenergic receptor blockade in nonobese normotensive humans on glucose and lipoprotein homeostasis, we assessed SI (determined by the minimal model method of Bergman), before and after glucose load plasma, glucose, and insulin levels, serum total triglycerides and lipoprotein cholesterol fractions, and some other variables in 20 healthy young men (26 +/- 1 years old, mean +/- SEM) during placebo and after 5 weeks of terazosin administration at a dose up to 10 mg once daily. Measurements were made after 3 days of standard diet (2,500 kcal/day, 45% carbohydrates, 40% fat, and 15% proteins) and after an overnight fast. Compared to placebo, terazosin decreased the upright systolic blood pressure (placebo vs. terazosin: 125 +/- 2 vs. 117 +/- 2 mm Hg, p less than 0.05) and increased supine (63 +/- 2 vs. 70 +/- 1 beats/min, p less than 0.05) and upright (77 +/- 2 vs. 88 +/- 2 beats/min, p less than 0.01) heart rates, while the body weight was unaltered. Terazosin did not significantly modify fasting plasma glucose (5.08 +/- 0.09 vs. 5.23 +/- 0.08 mmol/L, respectively), or insulin (8.9 +/- 0.5 vs. 8.6 +/- 0.6 microU/ml), SI (14.3 +/- 1.8 vs 11.8 +/- 1.5 x 10(-4)/min/microU/ml), the areas under the insulin or glucose curves, serum total triglycerides, and cholesterol or lipoprotein cholesterol fractions.(ABSTRACT TRUNCATED AT 250 WORDS)