AJP - Renal Physiology, Vol 260, Issue 4 590-F595, Copyright © 1991 by American Physiological Society
ANP stimulates phospholipase C in cultured RIMCT cells: roles of protein kinases and G protein
T. Berl, J. Mansour and I. Teitelbaum
Department of Medicine, University of Colorado School of Medicine, Denver 80262.
We examined the possibility that, in addition to stimulation of guanylate
cyclase (GC), atrial natriuretic peptide (ANP) also activates phospholipase
C (PLC) in cultured rat inner medullary collecting tubule (RIMCT) cells.
ANP (10(-12)M) causes marked release of inositol trisphosphate (IP3) at a
concentration that does not stimulate GC. Concentrations of ANP that
stimulate GC (greater than or equal to 10(-10) M) result in attenuated IP3
release. Similarly, exogenous dibutyryl guanosine 3',5'-cyclic
monophosphate (10(-6) M) markedly inhibits the response to 10(-10) M ANP.
Inhibition of cyclic nucleotide-dependent protein kinase by H 8, but not
inhibition of protein kinase C by H 7, restores the response to 10(-8) and
10(-6) M ANP. Therefore, activation of cyclic nucleotide-dependent protein
kinase inhibits ANP-stimulated PLC activity. Activation of protein kinase C
by phorbol 12-myristate-13-acetate (PMA) decreases ANP-stimulated IP3
production. Pretreatment with H 7, but not H 8, prevents inhibition by PMA.
To explore a potential role for G proteins, we examined the effect of
guanine nucleotide analogues on ANP-stimulated IP3 production in
saponin-permeabilized cells. ANP-stimulated IP3 production is enhanced by
GTP gamma S and is inhibited by GDP beta S. Similarly, preincubation with
pertussis toxin prevents ANP-stimulated IP3 release. We conclude that ANP
stimulates PLC in RIMCT cells via a pertussis toxin-sensitive G protein.
Stimulation of PLC is inhibited on activation of either cyclic nucleotide
or Ca2+-phospholipid dependent protein kinases.
