Influence of alpha and beta adrenergic receptors blockade on the adrenolytic effect of muscular work.
The changes in the response of adrenergic receptors alpha and beta in the blood vessels in the working muscles in a hindlimb in cats were studied after intra-arterial administration of noradrenaline, isoprenaline and during electric stimulation of the sympathetic trunk. The experiments were carried out during alpha-adrenergic receptors blockade with dihydroergotamine (0.3 mg/kg) beta-adrenergic receptors blockade with propranolol (1 mg/kg) and blockade of acetylcholine M receptors with atropine (0.5 mg/kg). The investigations were performed at rest, during exercise (electric stimulation of the sciatic nerve) and after the exercise. The following results deserve attention: 1) beta-adrenergic receptors blockade reduced significantly the alpha-adrenolytic effect of exercise restoring the ability of blood vessel to constriction in response to noradrenaline; 2) the vasodilator effect of isoprenaline evident in resting state and maintained to some extent during exercise was abolished completely by preceding alpha-adrenergic blockade. The changes in the reactivity of resistance vessels in working skeletal muscles to noradrenaline, with abolition of its vasoconstrictor effect, have been shown by Rein [7] and others authors [2, 5]. Similarly, it is well known that the resistance vessels contain two types of adrenergic receptors alpha and beta, and that the response of the vessels to stimulation of these receptors are different [1]. In view of the recently published observations of Jarhult and Lundvall suggesting that the beta-adrenergic receptors play an important physiological role [6] in the arterial part of the microcirculation [6] and in view of the hypothesis put forward by Kunos and Szentivanyj that alpha and beta receptors can be transformed depending on the intensity of tissue metabolism [8] it seemed worth while to study more systematically the changes of the reactivity of alpha and beta adrenergic receptors in the vascular bed of the skeletal muscles during and after muscle exercise.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001808:Blood Vessels / Q000294:innervation*; D002415:Cats; D004087:Dihydroergotamine / Q000494:pharmacology; D005260:Female; D006728:Hormones / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009132:Muscles / Q000098:blood supply*; D009638:Norepinephrine / Q000494:pharmacology; D005082:Physical Exertion; D011433:Propranolol / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D014662:Vasoconstrictor Agents
D006728:Hormones; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D014662:Vasoconstrictor Agents; D004087:Dihydroergotamine; D001285:Atropine; D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine