Resistance and capacitance functions of veins in the gastrocnemius muscle during electrical stimulation of ventral subdivisions of medulla oblongata

Abstract

Perfusion of blood vessels in the gastrocnemius muscle with autoblood under local electrostimulation of pressure zones of ventral part of the medulla oblongata revealed increments in resistance to blood flow in the muscle veins and arteries, which were respectively, 83 and 81% of the constrictor reactions of these vessels in response to a supramaximum electrostimulation of the sympathetic chains, while decrease in the venous blood filling was 33%. In response to electrostimulation of VMO depressor zones, the venous blood filling did not increase, while in the muscle arteries and veins the resistance to blood flow decreased by 60 and 130% in comparison with the dilator reactions of these vessels after dissection of sciatic nerve in the muscle preparation. Both quantitative and qualitative aspects of resistance and capacitance function of venous and resistive arterial vessels are shown to depend on individual features in the regulation of veins and arteries at the central and peripheral level. Key Words: ventral surface of medulla oblongata; venous resistance and capacitance function; gastrocnemius muscleAccording to modern views [4,7,9], ventral subdivisions of the medulla oblongata (VMO) contain populations of neurons, electrostimulation (ES) of which induces pressor or depressor shifts in systemic arterial pressure (AP) and the corresponding alterations in regional hemodynamics. There are no data in the literature on the effect of local ES of VMO on venous resistance to blood flow, which characterizes the resistance function of peripheral veins [6].Our aim was to compare dynamic changes of venous resistance to blood flow (venous resistance