ABSTRACT
Changes in pulmonary microcirculation were studied in isolated perfused rabbit lungs during modelling pulmonary thromboembolism under conditions of acetylcholine infusion against the background of treatment with M1 acetylcholine receptor blocker pirenzepine or blockade of muscarinic acetylcholine receptors with atropine. In the first case, the increase in pulmonary artery pressure was less pronounced than in case of atropine treatment. In response to pulmonary embolism after acetylcholine infusion against the background of pirenzepine pretreatment, the capillary hydrostatic pressure and postcapillary resistance did not change, while after atropine treatment, these parameters increased. In case of pulmonary embolism after acetylcholine infusion combined with selective blockade of M1 muscarinic acetylcholine receptors, the capillary filtration coefficient increased to a greater extent, than in the control and after blockade of muscarinic acetylcholine receptors.
Subject(s)
Muscarinic Antagonists/pharmacology , Pulmonary Circulation/drug effects , Pulmonary Embolism , Acetylcholine/pharmacology , Animals , Atropine/pharmacology , Blood Pressure/drug effects , Disease Models, Animal , Lung/blood supply , Lung/drug effects , Microcirculation/drug effects , Nitroglycerin/pharmacology , Pulmonary Circulation/physiology , Pulmonary Embolism/pathology , Pulmonary Embolism/physiopathology , Rabbits , Receptors, Muscarinic/drug effects , Receptors, Muscarinic/metabolism , Vascular Resistance/drug effects , Vascular Resistance/physiologyABSTRACT
In experiments on isolated perfused rabbit lungs, we studied changes in the pulmonary microcirculation in response to carvedilol injection and after modelling pulmonary thromboembolism under conditions of α1- and ß1,2-adrenoceptor blockade with this drug. Carvedilol had mainly vasodilator effects on the pulmonary arterial vessels; the pulmonary venous resistance increased and the capillary filtration coefficient remained unchanged under these conditions. In case of pulmonary thromboembolism against the background of carvedilol treatment, the increase in precapillary resistance and the capillary filtration coefficient was more pronounced that in the control, but the postcapillary resistance increased to a lesser extent. The increase in the capillary filtration coefficient is a result of elevated precapillary resistance and enhanced endothelial permeability.
Subject(s)
Carvedilol/therapeutic use , Pulmonary Circulation/drug effects , Pulmonary Circulation/physiology , Pulmonary Embolism/drug therapy , Pulmonary Embolism/physiopathology , Animals , Lung/drug effects , Lung/physiopathology , Pulmonary Veins/drug effects , Pulmonary Veins/physiopathology , RabbitsABSTRACT
Changes in the pulmonary microcirculation in isolated perfused rabbit lungs during modeling of pulmonary thromboembolism were studied in control animals and against the background of α-adrenoceptors blockade with phentolamine. Intravenous injection of emboli to control animals was followed by an increase in pressure in the pulmonary artery, mean capillary hydrostatic pressure, capillary filtration coefficient, pulmonary vascular resistance, as well as precapillary and postcapillary resistances. Against the background of α-adrenoceptor blockade, the increase in most parameters was less pronounced than in control animals, while capillary filtration coefficient increased more drastically. Thus, adrenergic mechanisms are involved in the constrictor reactions of both arterial and venous pulmonary vessels under conditions of pulmonary thromboembolism.
Subject(s)
Adrenergic alpha-Antagonists/pharmacology , Lung/drug effects , Microcirculation/drug effects , Phentolamine/pharmacology , Pulmonary Embolism/drug therapy , Receptors, Adrenergic, alpha/metabolism , Animals , Blood Pressure/drug effects , Capillary Permeability/drug effects , Disease Models, Animal , Lung/blood supply , Lung/metabolism , Lung/physiopathology , Organ Culture Techniques , Perfusion , Pulmonary Artery/drug effects , Pulmonary Artery/metabolism , Pulmonary Artery/physiopathology , Pulmonary Embolism/metabolism , Pulmonary Embolism/physiopathology , Pulmonary Veins/drug effects , Pulmonary Veins/metabolism , Pulmonary Veins/physiopathology , Rabbits , Vascular Resistance/drug effects , Vasoconstriction/drug effectsABSTRACT
Inhibition of the contractile activity of the stomach induced by psychogenic stress persisted after blockade of muscarinic and nicotinic cholinergic receptors and α2 and ß1/ß2-adrenergic receptors. Stress-induced increase in contractile activity in the proximal part of the duodenum persisted during blockade of muscarinic and nicotinic cholinergic receptors, ß1/ß2-adrenergic receptors. At the same time, blockade of the above cholinergic and adrenergic receptors eliminated the stress-induced increase in contractive activity in the distal part of the duodenum.
Subject(s)
Gastrointestinal Motility , Animals , Duodenogastric Reflux/psychology , Duodenum/physiopathology , Male , Muscarinic Antagonists/pharmacology , Muscle Contraction , Muscle, Smooth/physiopathology , Nicotinic Antagonists/pharmacology , Rabbits , Stress, Psychological/physiopathologyABSTRACT
The rabbits were exposed twice to stress, fixation to a frame in the supine position, for 60 min. Contractile activity of all portions of the large intestine was shown to increase significantly during the poststress period. These changes were not observed under conditions of blockade of muscarinic and nicotinic receptors. This state can be considered as dyskinesia impairing large intestinal transit of chyme.
Subject(s)
Hexamethonium Compounds/pharmacology , Intestine, Large/physiopathology , Muscarinic Antagonists/pharmacology , Muscle Contraction/drug effects , Nicotinic Antagonists/pharmacology , Oxyphenonium/pharmacology , Stress, Psychological/physiopathology , Action Potentials , Adrenergic beta-Antagonists/pharmacology , Animals , Female , Gastrointestinal Motility/drug effects , Intestine, Large/drug effects , Male , Propranolol/pharmacology , Rabbits , Restraint, PhysicalABSTRACT
Psychogenic stress in rabbits induced by fixation of the animals to a frame was accompanied by an increase in contractile activity of the duodenum. Against the background of blockade of muscarinic and nicotinic cholinergic receptors and ß(1)/ß(2)-adrenoceptors this increase was observed in postpyloric portion, but not in the distal third of the duodenum. The increase in contractile activity was determined by the direct effect of the hormonal stress factor on smooth muscles in the first case and by the influence of circulating catecholamines on excitatory ß-adrenoceptors of cholinergic neurons of the enteral nervous system in the second.
Subject(s)
Duodenum/physiology , Muscle Contraction/physiology , Peristalsis/physiology , Stress, Psychological , Adrenergic beta-1 Receptor Antagonists/pharmacology , Adrenergic beta-2 Receptor Antagonists/pharmacology , Animals , Catecholamines/blood , Catecholamines/metabolism , Cholinergic Neurons , Duodenum/metabolism , Enteric Nervous System , Motor Activity/drug effects , Muscarinic Antagonists/pharmacology , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Muscle, Smooth/physiology , Nicotinic Antagonists/pharmacology , Peristalsis/drug effects , Rabbits , Receptors, Adrenergic, beta-1/drug effects , Receptors, Adrenergic, beta-1/physiology , Receptors, Adrenergic, beta-2/drug effects , Receptors, Adrenergic, beta-2/physiology , Receptors, Muscarinic/metabolism , Receptors, Nicotinic/metabolismABSTRACT
Psychogenic stress in rabbits (fixation to a frame) was accompanied by the inhibition of contractile activity of the gastric antrum and pylorus. These changes persisted during blockade of muscarinic receptors, nicotinic receptors, alpha(2)-adrenoceptors, and beta(1)/beta(2) adrenoceptors. A stress-induced decrease in gastric motor activity was mediated by the nonadrenergic noncholinergic mechanism. It resulted from the influence of a hormonal stress factor on the stomach, which was probably realized through nonadrenergic inhibitory neurons of the enteric nervous system.
Subject(s)
Pyloric Antrum/physiopathology , Pylorus/physiopathology , Stress, Psychological/physiopathology , Adrenergic alpha-2 Receptor Antagonists , Adrenergic alpha-Antagonists/pharmacology , Adrenergic beta-Antagonists/pharmacology , Animals , Dihydroergotoxine/pharmacology , Ganglionic Blockers/pharmacology , Gastrointestinal Motility/drug effects , Gastrointestinal Motility/physiology , Hexamethonium Compounds/pharmacology , Male , Muscarinic Antagonists/pharmacology , Muscle Contraction/drug effects , Muscle Contraction/physiology , Muscle, Smooth/physiopathology , Oxyphenonium/pharmacology , Propranolol/pharmacology , Pyloric Antrum/drug effects , Pylorus/drug effects , Rabbits , Receptors, Adrenergic, beta/metabolism , Receptors, Muscarinic/metabolism , Receptors, Nicotinic/metabolism , Yohimbine/pharmacologyABSTRACT
Chronic experiments on rabbits showed that stress modeled by immobilization in the supine position induced different motor reactions in the gastroduodenal and ileocecal zones. Stress inhibited contractile activity in the stomach antrum, distal ileum, ileocecal valve area, and proximal colon and stimulated it in the duodenum. In the pyloric portion of the stomach both the inhibitory and potentiating effects of stress were observed.