Adrenergic Regulation of Myocardial and Vascular Function in Hypothermia

Regulation of the cardiovascular system in hypothermia and after its exposure is one of the important and urgent issues of biomedical research. This is due both to the severe consequences of hypothermia and to the potential benefits of its use for medical purposes. Adrenergic regulation is key for the normal functioning of the cardiovascular system. There are three groups of adrenergic receptors, α1, α2, and β, which are expressed in different proportions in the myocardium and blood vessels. Activation of each of the subtypes of adrenoreceptors can cause multidirectional effects, which are largely modified at low temperatures. The effectiveness of β-adrenergic stimulation decreases and can even act unidirectionally with hypothermia, leading to disorders in the work of the myocardium. The severity of the effects of α1-adrenoagonists in the heart and blood vessels also decreases; however, sensitivity to stimulation of α1a receptors in blood vessels may increase. Activation of this type of receptor has a cardioprotective effect. Activation of α2-adrenergic receptors also causes a wide range of cardioprotective effects. At the same time, there is evidence of direct inotropic and vascular effects mediated by this type of receptor. There is some evidence of an increase in these effects in hypothermia. The present review considers the current state of research on the effects of stimulation of certain types of adrenoreceptors in normal and hypothermic conditions. The mechanisms of physiological effects and the prospects for their further research are discussed.