Effects of long-term infusions of dopa and carbidopa on renin and steroid secretion in the rat.
Plasma, kidney, and adrenal catecholamine concentrations were varied by infusing rats with L-dopa and/or carbidopa for 2 weeks. L-Dopa infusion (300 micrograms/day) increased dopamine concentrations in plasma, adrenal zona glomerulosa, and kidney by 140%, 74%, and 224%, respectively: the dopamine content of the adrenal inner cortex plus medulla was not increased. Infusion of carbidopa alone had no detectable effect upon endogenous dopamine concentrations. Concomitant infusion (300 micrograms/day) of carbidopa with L-dopa blocked the rise in plasma and adrenocortical dopamine caused by L-dopa alone. Plasma aldosterone and plasma and kidney active renin concentrations were unaffected by L-dopa administration but plasma corticosterone and deoxycorticosterone (DOC) were significantly elevated (P < 0.05); increases in DOC appeared greater than those of corticosterone. These data cast doubt on the theory that dopamine is a physiological tonic inhibitor of aldosterone synthesis in rats. However, in the rat, stimulatory effects of L-dopa on plasma concentrations of precursors of aldosterone might be of physiological significance since DOC is a potent mineralocorticoid.
Inglis
G C
GC
MRC Blood Pressure Unit, Western Infirmary, Glasgow, United Kingdom.
Kenyon
C J
CJ
D000302:Adrenal Cortex / Q000187:drug effects / Q000378:metabolism; D000305:Adrenal Cortex Hormones / Q000378:metabolism*; D000450:Aldosterone / Q000097:blood; D000818:Animals; D002230:Carbidopa / Q000008:administration & dosage / Q000494:pharmacology*; D003345:Corticosterone / Q000097:blood; D003900:Desoxycorticosterone / Q000097:blood; D004295:Dihydroxyphenylalanine / Q000008:administration & dosage / Q000494:pharmacology*; D004298:Dopamine / Q000097:blood / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012083:Renin / Q000378:metabolism*
D000305:Adrenal Cortex Hormones; D003900:Desoxycorticosterone; D000450:Aldosterone; D004295:Dihydroxyphenylalanine; D012083:Renin; D002230:Carbidopa; D004298:Dopamine; D003345:Corticosterone