Anti sense DNA down-regulates proteins kinase C-epsilon and enhances vasopressin-stimulated Na+ absorption in rabbit cortical collecting duct.
AUTOR(ES)
DeCoy, D L
RESUMO
Hormonal activation of protein kinase C (PKC) is a major signaling mechanism regulating salt and water transport in the distal nephron. We used antisense DNA to down-regulate a PKC isoform in the rabbit cortical collecting duct (CCD) and examined its role in mediating arginine vasopressin's (AVP) effect on salt transport in the CCD. Immunoblots demonstrate that PKC-epsilon (diacylglycerol sensitive) and PKC-zeta (diacylglycerol insensitive) are the major PKC isoforms in both freshly isolated and primary cultures of rabbit CCDs. Rabbit CCDs grown on semi-permeable supports, displayed a positive baseline short circuit current (Isc), which was abolished by amiloride, demonstrating active Na+ absorption. Both AVP and 8-chloro-phenylthio-cAMP (8CPTcAMP) transiently increased Isc, however, within 40 min Isc fell below baseline. Down-regulation of PKC-epsilon, as confirmed by immunoblot, was achieved either by treatment with a PKC-epsilon-specific antisense oligonucleotide or 48 h of 1 microM PMA. In PKC-epsilon down-regulated cells, 8CPTcAMP produced a sustained, rather than transient, increase in Isc. We suggest cAMP stimulates Na+ transport, but secondary activation of PKC-epsilon results in the sustained inhibition of Na+ transport seen in response to vasopressin in the CCD.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=295959Documentos Relacionados
- Endothelin inhibits vasopressin-stimulated water permeability in rat terminal inner medullary collecting duct.
- Atrial natriuretic factor inhibits vasopressin-stimulated osmotic water permeability in rat inner medullary collecting duct.
- Luminal vasopressin modulates transport in the rabbit cortical collecting duct.
- Vasopressin-stimulated phosphoinositide hydrolysis in cultured rat inner medullary collecting duct cells is mediated by the oxytocin receptor.
- Cyclic adenosine monophosphate-stimulated anion transport in rabbit cortical collecting duct. Kinetics, stoichiometry, and conductive pathways.