[Effect of adaptation to cold on the alpha1- and beta-adrenergic reactions of arterial vessels of the small intestine in rabbits].

Changes in major paraments of alpha 1- and beta-adrenergic responses (EC50 and Pm) were studied in the intestine arterial blood vessels of rabbits adapted to cold for 1-30 days (daily cold exposures for 6 hours at -10 degrees C). It was shown that responses to phenylephrine, noradrenaline, adrenaline (alpha 1-agonists), isopropylnoradrenaline (beta-agonist) corresponded to the equation p = (Pm.An)/(EC50n + An) with n = 1 and n = 2, respectively.

[Changes in alpha1-, alpha2-, and beta-adrenergic responses of blood pressure in blood vessels of the rabbit hindlimbs during cold adaptation].

Changes in major parameters of alpha 1-, alpha 2- and beta-adrenergic responses (EC50 and Pm) were studied in hind-limb arterial vessels of the rabbits adapted to cold for 1-30 days (daily cold exposures for 6 hours at -10 degrees C). It was shown that responses to phenylephrine, noradrenaline, adrenaline (alpha 1-agonists), clondine (alpha 2-agonist), isopropylnoradrenaline (beta-agonist) corresponded to the equation p = (Pm.An)/(EC50n = An) with n = 1 and n = 2, respectively.

Interactions of radiolabelled ligands with specific receptors: an analysis.

The binding and displacement of beta-adrenoceptor blockers, [3H]propranolol ([3H]PRP) and [3H]dihydroalprenolol ([3H]DHA), were studied on isolated rat erythrocytes, their membranes and ghosts; the binding of [3H]DHA and a M-cholinoceptor blocker, [3H]quinuclidinylbenzylate ([3H]QNB), on cerebral cortex membranes. In all experiments, ligand-receptor interactions conformed to a model of two pools of receptors in the same effector system and the binding of two ligand molecules to the receptor. The results were similar for the displacement of [3H]PRP, [3H]DHA and [3H]QNB with propranolol, dihydroalprenolol and quinuclidinyl-benzylate, respectively.

[Effect of cocaine on the contractile response to noradrenaline in the epididymal and prostatic regions of the vas deferens].

In the prostatic half of the rat vas deferens, the response to noradrenaline under the cocaine effect revealed a phasic and a tonic components, whereas in the epididymal portion of the vas deferens there only occurred the tonic component. Cocaine increased the maximal tonic contractile response to noradrenaline in the epididymal portion and the maximal phasic response--in the prostatic one. Mechanisms of direct postsynaptic action of cocaine are discussed.

An approach to analysis of radiolabeled ligand interactions with specific receptors.

The aim of the study was to reveal general characteristics of the ligand-receptor interaction in the binding and displacement of radiolabeled ligands. The binding and displacement of DL-[3H]propranolol hydrochloride ([3H]propranolol) and L-[propyl-2,3, -3H]dihydroalprenolol ([3H]dihydroalprenolol), beta-adrenoceptor antagonists, were studied with isolated rat red blood cells, their membranes and ghosts. The binding of [3H]dihydroalprenolol and L-quinuclidinyl-[phenyl-4-3H]-benzylate ([3H]quinuclidinyl benzylate), a muscarinic acetylcholine receptor antagonist, was studied with cerebral cortex membranes.

[Quantitative analysis of ligand-receptor interactions in physiological experiments].

In isolated smooth muscles of the sea cucumber, the rat intestine, vas deferens and portal vein, and in chick embryonic amnion, contractile responses of smooth muscles to transmitters and their agonists were described with two equations: p = (Pm.A(n))/(EC50n + A(n)) [7] or p = [(Pm1.An1)/(EC50(1)n1 + An1)] + [(Pm2.

[The characteristics of the binding of M-cholinergic blockers and beta-adrenoblockers by the brain synaptosomes of 15-day-old and adult rats].

Significant difference in values of basic parameters, Bmax and Kd which characterize binding of 3H-quinuclidynylbenzylate and 3H-dihydroalprenolol, specific blockers of m-cholino- and beta-adrenoreceptors, has been established for brain synaptosomes from 15-day and adult rats. It was shown that phospholipase A2 (1 microgram/ml), a membrane active component from the venom of the cobra Naja naja oxiana, reduced Bmax and Kd for binding 3H-quinuclidynylbenzylate and 3H-dihydroalprenolol by synaptosomes. It is suggested that functional modifications in membrane during animal development or induced by phospholipase A2 result in shifts in the specific activity of adreno- and cholinoreceptors and, as a result, in disturbances of adrenergic and cholinergic responses.

[Modulation of the M-cholinergic reaction by the venom of the Central Asian cobra (Naja naja oxiana)].

The effect of the Central Asian cobra's (Naja naja oxiana) poison upon cholinergic response of isolated small intestine was studied in the Wistar rats. The effect involved a significant activation by 30-70 per cent of M-cholinergic response in the type of "noncompetitive" interaction. The modulating effect of the poison is supposed to occur due to changes in cytoplasmatic membrane.

[Use of Naja oxiana venom for modulating the adrenergic process].

Specific changes of adrenergic responses to the poison of the Middle Asia cobra were found in the rat isolated small intestine. The changes reminded the action of inhibitors upon enzymes and may be characterized as a partial competitiveless interaction. The poison modulating effect upon adrenergic responses seem to be unrelated to its direct action on adrenoreceptors, but mediated through the effector cell's membrane.