The mechanism of the dipsogenic action of synthetic tetradecapeptide renin substrate (TDP) was studied in rats with chronically implanted lateral ventricular cannulae. All hormones and drugs were injected via the ventricular cannulae. The dipsogenic action of TDP was unaffected by the renin inhibitor pepstatin but was markedly reduced by the angiotensin converting enzyme inhibitor SQ 20881. Homogenates of rat brain readily formed angiotensin II from TDP in vitro and this was likewise unaffected by pepstatin but was reduced or abolished by SQ 20881 or by chelating agents. Natural renin substrate did not cause drinking and did not generate angiotensin II when incubated with brain homogenates. These results demonstrate that rat brain converting enzyme can generate angiotensin II from TDP and that this effect is responsible for the dipsogenic action of TDP.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Clinical Neurology
- Developmental Biology