Renal Na+ -K+ - ATPase in Weanling and Adult Spontaneously Hypertensive Rats
Publisher website: http://www.ebmonline.org
NOTE: At the time of publication, the author Susan C. Opava-Stitzer was affiliated with the University of Puerto Rico School of Medicine - San Juan, Puerto Rico. Currently, April 2008, she is Dean of Research and Graduate Programs at California Polytechnic State University - San Luis Obispo.
The interrelationships among plasma renin activity (PRA, ng AI/ml plasma/hr), aldosterone concentration (ng%), and renal Na+-K+-ATPase activity (μmole P04/mg protein/ hr) were studied in 9 weanling normotensive spontaneously hypertensive rats (SHR), 9 adult hypertensive SHR, and 9 weanling and 9 adult normotensive Wistar-Kyoto rats (WKY). All groups were placed on a normal (0.4% sodium) diet. PRA and plasma aldosterone, measured in samples drawn from the ether-anesthetized rat, were higher in weanling SHR (15.2 ± 2.0, 37 ± 4.2) than in WKY. PRA measured in samples collected from a separate group of unanesthetized weanling SHR was also greater than in age-matched WKY. In adult SHR, PRA (6.1 ± 0.9) and plasma aldosterone (20.0 ± 2.7) were decreased. During the weanling period Na+-K+-ATPase activity in SHR was not only greater than in age-matched WKY but was also increased compared to adult normotensive and hypertensive rats (137 ± 9 weanling SHR, 89 ± 7 weanling WKY, 73 ± 11 adult SHR, 84 ± 17 adult WKY). Thus, during the weanling period the renin-angiotensin-aldosterone (R-A-A) system and renal Na+-K+-ATPase activity are activated in SHR. The elevation of Na+-K+-ATPase activity may be due to increased aldosterone levels. It was noted, however, that plasma aldosterone was similar in adult WKY and weanling SHR, while Na+-K+-ATPase activity was higher in SHR. These findings involving R-A-A and renal Na+-K+-ATPase activity prior to the elevation of blood pressure suggest that the kidneys may play a role in the initiation of hypertension in SHR.
Jose L. Cangiano, Carmen Rodriguez-Sargent, Susan C. Opava-Stitzer, and Manuel Martinez-Maldonado. "Renal Na+ -K+ - ATPase in Weanling and Adult Spontaneously Hypertensive Rats" Proceedings of the 1984 Society for Experimental Biology and Medicine 177 (1984): 240-246.
Available at: http://works.bepress.com/sopava/7