[Adrenoreactivity of the vessels of the small intestine during adaptation to high altitude in the cat]

Abstract

Responses of the resistance and capacitance vessels of small intestine to adrenergic stimulation and blockade were studied in acute experiments on cats after 3-30 days of high altitude adaptation (the Pamirs, 3370 m). In comparison to control (Dushanbe, 830 m) constrictor responses of the resistance vessels to noradrenaline and adrenaline were significantly increases at high altitude, whereas the dilator responses to beta-stimulator propranolol were obviously reduced. Changes of venous blood outflow from small intestine in response to catecholamines at high altitude exceeded the control values. Pharmacological analysis suggests that the reactivity of alpha-adrenoreceptors of the small intestine resistance and capacitance vessels at high altitude was increased, whereas the beta-reactivity of the resistance vessels was reduced. Crucial shifts of the adrenoreactivity occurred after 3-5 and 14-16 days of the adaptation.