I. C. Roddie

Comparison of the effects of I.C.I. 50172 and propranolol on the cardiovascular responses to adrenaline, isoprenaline and exercise

1 The intravenous infusion of I.C.I. 50172 in doses up to 20 mg reduced, although not significantly, the increase in heart rate produced by the infusion of isoprenaline in healthy volunteers; the response to adrenaline was significantly reduced. The infusion of 1 mg propranolol abolished these responses 2 After the pre‐treatment of subjects with atropine or hexamethonium, I.C.T. 50172 produced a significant reduction in an isoprenaline tachycardia. This reduction was not competitive and did not exceed 50%. 3 The intravenous injection of 4 mg I.C.I. 50172 reduced an exercise tachycardia; its effect was less than that of 4 mg propranolol. This difference became greater as the doses of the two drugs were increased. The dextro isomer of propranolol had no effect on the exercise tachycardia; I.C.I. 45763 reduced it to the same extent as propranolol. 4 The intravenous injection of I.C.I. 50172 reduced the increase in heart rate produced by tilting a normal subject from the supine to 80° head‐up position. After the administration of atropine, I.C.I. 50172 almost abolished the response. In the presence of atropine, I.C.I. 50172 was as active as propranolol in reducing the increase in heart rate on tilting. 5 The reason for the differences in the effects of I.C.I. 50172 on the increases in heart rate brought about by the three procedures is not clear. 6 The increase in forearm blood flow produced by the infusion of isoprenaline into the brachial artery was not reduced by the intra‐arterial administration of I.C.I. 50172.

The effect of β-adrenoceptor blockade on human sweating

1 Changes in cutaneous water loss were followed by continuously monitoring total body weight loss. 2 Sweating was induced in normal subjects by raising the environmental temperature or by subjecting them to the emotional stress of mental arithmetic. 3 Propranolol in a dosage of 0·15 mg/kg body weight intravenously had no significant effect on either thermal or emotional sweating, whereas thermal sweating was completely blocked temporarily by administration of atropine 2·4 mg intravenously. 4 It is concluded that β‐adrenoceptor blockade has no effect on physiological sweating in normal people.

Sweat responses of a hyperhidrotic subject

Sweating was measured in a subject presenting with palmar hyperhidrosis. The skin of his whole body appeared to sweat excessively in response to mental but not to thermal stress, compared with normal subjects.