Are cardiac G-proteins altered in rat models of hypertension?
OBJECTIVE
To determine whether alterations in cardiac G-protein number or function, or both, are involved in the desensitization of adenylate cyclase responsiveness in the hypertensive state.


METHODS
Quantitation of G-protein subunits in myocardial membranes from four different rat models of hypertension in comparison with respective normotensive rats.


METHODS
We compared male and female adult spontaneously hypertensive rats (SHR) with age- and sex-matched Wistar-Kyoto (WKY) rats, rats from the highest-pressure quartile from an F2 generation of WKY x SHR hybrids with those from the lowest-pressure quartile, and one-kidney, one clip renal hypertensive with sham-operated rats. The function of Gs alpha was quantitated by reconstitution of cardiac cholate extracts into cyc- cell membranes with subsequent measurement of NaF-stimulated adenylate cyclase activity. The amounts of immunodetectable Gs alpha, Gi alpha, Gq alpha and G beta were determined from quantitative Western blotting experiments with [125I]-protein A detection.


RESULTS
None of the parameters investigated differed significantly between hypertensive and normotensive rats in any of the models investigated.


CONCLUSIONS
We conclude that major quantitative alterations in cardiac Gs, Gi or Gq are not a general feature of the hypertensive state.
Michel
M C
MC
Department of Pharmacology, University of California San Diego, La Jolla.
Brodde
O E
OE
Insel
P A
PA
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D006973:Hypertension / Q000209:etiology / Q000378:metabolism*; D006978:Hypertension, Renovascular / Q000209:etiology / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011943:Receptors, Adrenergic, beta / Q000378:metabolism
D011943:Receptors, Adrenergic, beta; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases