Abstract
Proper adjustment of renin‐angiotensin system activity is believed to be important to maintain normal blood pressure during high salt intake. The median preoptic nucleus (MnPO) receives afferent inputs from the subfornical organ and organum vasculosum of lamina terminalis, the circumventricular organs that have been shown to be necessary in central effects of angiotensin II involving sodium and water homeostasis. In this study, we hypothesized that an intact MnPO is necessary for the long‐term control of arterial pressure during chronic changes in dietary salt. To test this hypothesis, male Sprague Dawley rats were subjected to either sham (SHAM) or electrolytic lesion of the entire MnPO (MnPOx). After a 1‐wk recovery period, rats were instrumented with radiotelemetric transducers, and aortic flow probes, for the 24 h‐measurement of mean arterial pressure (MAP) and heart rate, and cardiac output, respectively. After another 10 days of recovery period, the protocol was started with a 7‐day control period (1% NaCl diet) followed by a 14‐day high salt period (4% NaCl diet), and 7 day recovery period (1% NaCl diet). Daily water and sodium intake, output, and balance were recorded throughout the protocol. By day 10 of the high salt period, MAP in SHAM (n=3) and MnPOx (n=3) lesion rats had increased from baseline control level (8.5 ± 2.0 and 7.4 ± 1.2, respectively). The level of MAP during high salt intake was not significantly different between the two groups. These results do not support the hypothesis that the MnPO is necessary for normal arterial pressure regulation during chronic changes in dietary salt.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call