Woodard GE, Zhao J, Rosado JA. Different effect of ATP on ANP receptor guanylyl cyclase in spontaneously hypertensive and normotensive rats.
Acta Physiol (Oxf) 2006;
188:195-206. [PMID:
17054659 DOI:
10.1111/j.1748-1716.2006.01628.x]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
AIM
Natriuretic peptide receptor A (NPR-A) is the main physiological receptor for atrial natriuretic peptide (ANP). Maximal activation of NPR-A guanylyl cyclase (GC) requires ANP binding and ATP interaction with a putative cytoplasmic site. This study investigates the regulatory effect of ATP on GC-coupled NPR-A activity in Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR).
METHODS
Cyclic GMP production and competitive inhibition of [(125)I]ANP(1-28) binding were performed in solubilized glomerular and papillary renal membranes.
RESULTS
Here, we report that incubation of renal glomerular and papillary membranes with ATP induced a concentration-dependent increase in basal and ANP(1-28)-stimulated GC activity that was significantly greater in SHR than in age-matched WKY. ATPgammaS was more effective than ATP and induced a greater stimulation of cGMP production in SHR than in WKY. In contrast, in solubilized membranes ATP exerted an inhibitory role on basal and ANP(1-28)-induced GC activity, suggesting that an accessory protein is required for ATP-induced GC activation. ATP increases NPR-A affinity for ANP(1-28) and decreased B(max) in crude and solubilized membranes. Kinetic analysis of GC-coupled NPR-A revealed that ATP reduced the Km and increased the V(max), an effect that was greater in SHR.
CONCLUSION
Our observations indicate that ATP exerts a greater net effect on NPR-A in SHR than in WKY, which might explain the greater rate of cGMP production observed in SHR compared to WKY.
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