Published 4 issues per year
ISSN Print: 2155-014X
ISSN Online: 2155-0158
Modulation of Na+, K+-ATPase Activity in the Medulla Oblongata Neurons Affects Hemodynamics in Spontaneously Hypertensive Rats
ABSTRACT
The study was conducted on rats with normal arterial pressure (control) and spontaneously hypertensive rats, anesthetized with urethane (1600 mg / kg, i.p.). It has been shown that injections of ouabain (10−8 − 10−6 mol/), a specific Na+, K+-ATPase inhibitor, in the cardiovascular nuclei (nucleus tractus solitarius, NTS; paramedian reticular nucleus, PMn; lateral reticular nucleus, LRN) of the control rats are usually accompanied by a dose-dependent rise in the systemic arterial pressure. In spontaneously hypertensive rats, injections of ouabain in the studied medullary nuclei result in either hypertensive responses, which are more pronounced than those in the control rats, or hypotensive responses. An activation of Na+, K+-ATPase by injections of asparcam in the cardiovascular neurons within the medullary nuclei results in the development of hypotensive responses in both control animals and spontaneously hypertensive rats, but in the latter effect is more pronounced. In biochemical study, Na+, K+-ATPase activity in the microsomal fraction of the medulla oblongata of spontaneously hypertensive rats has been found to be 61.8% higher than the enzyme activity in normotensive animals. These data suggest that Na+, K+-ATPase of the cell plasmatic membranes in the medullary cardiovascular nuclei is involved in the neural control of blood circulation, and its inhibition promotes hypertension of central origin.