Dynamics of carotid sinus elasticity during pressor reaction.

• As it has been shown, the deformation of the vascular wall (and not the intravascular pressure by itself) may be considered as an adequate stimulus of the sinocarotid receptors. This fact, as well as the significance of pulsating pressure in excitation of these receptors,' 3 consequently prove that the elasticity of the sinocarotid region may be essential in. determining the excitation of the receptors. Little attention lias been focused, however, up to recently, on the study of elasticity of the sinocarotid region in vivo and in situ under physiological conditions. Considering the well-known fact that the elasticity coefficient (CE) increases with increasing pressure, it follows that in the course of pressor reaction, the CE might increase to a degree that even the greatest pulse pressure would not give rise to such a pulse volume (i.e., pulse deformation) as existed before the pressure rise. Under these circumstances, one must suppose that excitation of the receptors, which is —according to the above-mentioned data—dependent also on pulse deformation of the receptor area, might not be sufficiently activated. Thus, the regulatory mechanisms, if initiated at all, inight not be adequate to compensate for the given hypertensive situation. In previous papers,"• ° we demonstrated, however, that in the course of compensation of a hypotensive situation, significant changes (an increase) of the elasticity coefficient take place iu the sinocarotid region. We concluded then that these changes are indispensable for carrying out the normal function of the receptive apparatus.