Analysis of the time course for organ culture-induced endothelin ET B receptor upregulation in rat mesenteric arteries.

In contrast to the constitutively expressed endothelin ET(A) receptor, the distribution of endothelin ET(B) receptors is more variable. The aim of the present study was to investigate the kinetics of organ culture-induced upregulation of contractile endothelin ET(B) receptors in rat mesenteric arteries at both mRNA and functional levels. Assessment of mRNA expression revealed low levels of endothelin ET(B) receptor mRNA relative to endothelin ET(A) receptor mRNA after 3 h of culture, which gradually increased to reach a plateau level after 24 h. Correspondingly, vessels cultured for 3 h showed a negligible contractile response the selective endothelin ET(B) receptor agonist sarafotoxin 6c. Subsequently, the contractile response to sarafotoxin 6c was successively increased during organ culture until 24 h and, thereafter, a further increase in potency was seen after 48 h. These results demonstrate a rapid induction of transcription within less than 7 h followed by an increase in the response to receptor stimulation.