Stimulation of the renin-angiotensin system by growth hormone in Lewis dwarf rats.
A genetically growth hormone (GH)-deficient strain of Lewis rats was used to test the hypothesis that the actions of GH on electrolyte and fluid homeostasis are mediated by the renin-angiotensin-aldosterone system (RAAS). Dwarf rats injected with recombinant bGH (2 mg.kg-1 x day-1) for 7 days (group GH1+) and 28 days (group GH4+), respectively, were compared with saline-injected dwarf (group GH-) and normal (group N) Lewis rats. GH decreased Na+ excretion and increased renal glomerular filtration rate in dwarf rats. The dietary intake and plasma concentrations of Na+ and K+ remained unchanged. GH increased plasma insulin-like growth factor I (IGF-I) concentrations in dwarf rats (GH - = 109 +/- 9, GH1+ = 184 +/- 5, GH4+ = 189 +/- 28, N = 477 +/- 29 ng/ml plasma). Plasma angiotensinogen increased towards the levels found in normal Lewis rats (GH- = 859 +/- 38, GH1+ = 906 +/- 18, GH4+ = 1,027 +/- 19, N = 1497 +/- 80 ng angiotensin I/ml plasma); plasma renin activity increased above that of the normal Lewis (GH- = 10.2 +/- 0.6, GH1+ = 11.7 +/- 0.7, GH4+ = 16.7 +/- 2.4, N = 10.6 +/- 0.8 ng angiotensin I.ml plasma-1 x h-1). Plasma aldosterone, corticosterone, and triodothyronine concentrations were unchanged by GH treatment. Angiotensin II receptor densities in GH- rats (liver = 356 +/- 23, kidney = 228 +/- 28, adrenal = 478 +/- 58 fmol/mg protein) were upregulated by GH (GH4+ rats; liver = 573 +/- 27, kidney = 360 +/- 86, adrenal = 721 +/- 78 fmol/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)
Wyse
B
B
Department of Physiology and Pharmacology, University of Queensland, Brisbane, Australia.
Waters
M
M
Sernia
C
C
D000818:Animals; D001835:Body Weight; D004326:Drinking; D004392:Dwarfism / Q000473:pathology / Q000503:physiopathology*; D004435:Eating; D004573:Electrolytes / Q000378:metabolism; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006128:Growth; D013006:Growth Hormone / Q000494:pharmacology*; D006728:Hormones / Q000097:blood; D007668:Kidney / Q000378:metabolism; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D011917:Rats, Inbred Lew; D011945:Receptors, Angiotensin / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000502:physiology*
D004573:Electrolytes; D006728:Hormones; D011945:Receptors, Angiotensin; D013006:Growth Hormone