Apte, C VDikshit, M BPrasad, B A1992-07-012009-06-011992-07-012009-06-011992-07-01Apte CV, Dikshit MB, Prasad BA. Beta-adrenoreceptor blockade attenuates heat-induced tachycardia,but not the tolerance to the stress. Indian Journal of Physiology and Pharmacology. 1992 Jul; 36(3): 149-54http://imsear.searo.who.int/handle/123456789/107050Ten healthy males (age 34 +/- 3 yr 9 SE) underwent 40 min of heat exposure (WD 39.7.C) after 2 hours of ingesting 120 mg of Propranolol (Inderal; ICI), or a placebo, in a random manner, the exposures being about a week apart. That there was no placebo effect was ensured by giving a control run (no medication). In the placebo trials, the end-experiment heart rate had increased by 52%, while after propranolol the increase was only 43%. Regression analysis showed that with the placebo, the HR increased by 22 beats/min/o rise in core (aural) temperature, while with propranolol, the rise (14 beats/min) was significantly lower (P < 0.02). The various heat strain indices viz the Craig's Index, the Body heat storage (Kilocals/m2/hr), and the effective heat storage were also similar for both the treatments. We conclude that beta-adrenoreceptor activity plays a significant role in producing tachycardia of heat exposure in humans, but blocking this activity with propranolol does not affect tolerance to heat stress.engAdministration, OralAdultBlood Pressure --drug effectsBody Temperature --drug effectsHeart Rate --drug effectsHot Temperature --adverse effectsHumansMalePropranolol --administration & dosageReceptors, Adrenergic, beta --drug effectsStress, Physiological --physiopathologyTachycardia --etiologyClinical Trial