Всероссийский научно-исследовательский институт физиологии, биохимии и питания животных – филиал Федерального государственного бюджетного научного учреждения «Федеральный научный центр животноводства – ВИЖ имени академика Л.К. Эрнста»
ABSTRACT. The aim was to study the sensitivity of contractile cells of the cow’s udder vascular wall to acetylcholine, and to evaluate the role of the cholinergic mediator system in the control of mammary blood by efferent nerve fibers. Two experiments were conducted on 6 cows under endotracheal anesthesia. In first experiment, it has been studied the reaction of the udder’s blood vessels to acetylcholine introduced in external pudendal artery at a dose of 0.01-1 mg. In second experiment, the role of acetylcholine was studied in transmission of nerve impulses from the endings of postgangliar neurons to the udder’s vascular wall. Simultaneously, there were registered the blood pressure, the volume blood flow rate in half of the udder and calculated value of the udder’s vascular resistance. The data obtainned indicate that acetylcholine enhances the level of blood supply to the udder. The fact of constant systemic blood pressure indicates the local mechanism of the shifts in udder blood supply caused by a change in the tone of udder’s blood vessels. The experimental results suggest the presence of cholinergic receptors in the wall of blood vessels of the udder. The presence of the phase of initial rise in udder’s blood supply after injection of acetylcholine followed by a decrease may indicate a change in the tone of the blood vessels due to compression and expansion of the alveoli in the process of milk ejection. Acetylcholine is involved in the transmission of nerve impulses from the endings of postganglionar neurons to vascular wall of the udder. The data obtained suggest that the vasodilator component of the response to stimulation of the external seminal nerve may be due to the action of acetylcholine on the udder’s blood vessels.
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