ENDOTHELIN MODULATES DIHYDROPYRIDINE RECEPTOR DECREASED BINDING IN HIPPOCAMPAL SLICES FROM NORMOTENSIVE AND SPONTANEOUSLY HYPERTENSIVE RATS

Previous studies in rats have demonstrated both the link between volta ge-operated calcium channels and endothelin and their cerebral involve ment in the pathophysiology of spontaneous hypertension. In the presen t study, the interaction of endothelin with specific dihydropyridine ( DHP) binding sites was investigated using the brain slices model. In r at hippocampal slices, pre-incubation with Bay K 8644 decreased [H-3] (+) PN 200-110 binding. There was no difference in agonist-induced dec rease of DHP binding in normotensive and spontaneously hypertensive (S H) rats. The effect of Bay K 8644 was partially inhibited by endotheli n but not by angiotensin in both normotensive and hypertensive rats. T hese data compared to those of other studies suggest that DHP binding sites which are regulated by endothelin are post-synaptic. We conclude that brain slices provide a good in vitro model to study DHP receptor regulation and to explore endothelin interactions with DHP-sensitive Ca2+ channels.