Endothelin-1 affects AVP-stimulated cAMP but not ANP-induced cGMP productions in cultured rat IMCD cells

Summary: The present study was undertaken to explore a potential interaction of endothelin-1 (ET-1) on vasopressin (AVP)-dependent cyclic 3',5'-adenosine monophosphate (cAMP) and atrial natriuretic peptide (ANP)-dependent cyclic 3',5'-guanosine monophosphate (cGMP) metabolisms in primary cultured rat inner medullary collecting duct (IMCD) cells. Endothelin-1 did not affect ANP-stimulated cGMP accumulation in the presence or absence of 3-isobutyl-1-methylxanthine (IBMX). Levels of 10⁻¹⁰ to 10⁻⁷ mol/LET-1 showed a dose-dependent inhibition of the AVP-dependent cAMP accumulation in the presence of IBMX and 10⁻⁷ mol/LET-1 inhibited the cAMP generation by 34 ± 5.3% ( n = 5, n = 20, P <0.01). Endothelin-1 did not affect the cAMP generation either by 100 ng/mL cholera toxin or by 10⁻⁴ mol/L forskolin. Endothelin-1 failed to inhibit the cAMP generation in the presence of 100 ng/mL pertussis toxin (PTX). the inhibitory effect of ET-1 was reversed by 10⁻⁸ mol/L staurosporin (SSP), a protein kinase C (PKC) inhibitor. Furthermore, this inhibitory effect of ET-1 was mimicked by 10⁻⁸ mol/L phorbol 12-myristate 13-acetate (PMA), an activator of PKC. A dose of 5 × 10⁻⁶ mol/L indomethacin did not affect this inhibitory effect of ET-1. From these results, we suggest that the effect of ET-1 on cyclic nucleotides metabolism seem to be selective. Endothelin-1 did not affect the cGMP generation by ANP, whereas it inhibited cAMP production by AVP via PTX and SSP sensitive pathway in cultured rat IMCD cells.