Enhancement of physiological finger tremor by intravenous isoprenaline infusions in man: evaluation of its role in the assessment of beta-adrenoceptor antagonists.

Graded intravenous isoprenaline infusions produce dose-related increases in finger tremor. The dose-response curves constructed with intra-arterial or intravenous isoprenaline behave similarly in the presence of both atenolol 50 mg and propranolol 40 mg. In Five subjects, practolol 120 mg, atenolol 50 mg, propranolol 40 mg and sotalol 200 mg reduced exercise heart rate by 20.2 +/- 2.3, 21.4 +/- 1.8, 17.4 +/- 2.5, 23.9 +/- 3.6% respectively: the differences were not significant. The corresponding dose-ratios for reduction of an isoprenaline tachycardia were 2.8, 2.3, 19.1 and 16.9 respectively. At doses which had comparable effects on an exercise tachycardia, the non-selective beta-adrenoceptor antagonists, propranolol 40 mg and sotalol 200 mg, attenuated the finger response to isoprenaline (dose ratios 33.3 and greater than 25.0 respectively) more than the beta 1-selective adrenoceptor antagonists, practolol 120 mg and atenolol 50 mg (dose ratios 1.0 and 2.3 respectively). In two out of five subjects, dose-response curves could not be constructed with sotalol, either at a dose of 200 or 100 mg. The enhancement of physiological finger tremor by intravenous infusions of isoprenaline may be useful in the investigation of beta 2-adrenoceptors and their antagonists in man.