Role of alpha-adrenergic stimuli in the control of rat renal ammoniagenesis.
The effects of phenylephrine on renal ammoniagenesis and the involvement of Ca2+ in phenylephrine action were investigated in isolated proximal fragments of rat-kidney tubules. Phenylephrine stimulated renal ammoniagenesis from 1 and 2 mM glutamine whereas no significant changes took place at a higher concentration of glutamine (20 mM). Stimulation of ammonia synthesis by phenylephrine was found to be linear with time and dose-dependent between 10(-9) and 10(-4) M. Phenylephrine-stimulated ammoniagenesis was blocked by phentolamine (10 microM) but not by propranolol (10 microM) confirming that the effect is mediated by alpha-adrenergic stimuli. No stimulatory effect of phenylephrine was observed in Ca2+ depleted proximal tubule fragments, suggesting that Ca2+ is required in this adrenergic response.
García-Salguero
L
L
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Granada, Spain.
Hortelano
P
P
Lupiáñez
J A
JA
D000316:Adrenergic alpha-Agonists / Q000502:physiology*; D000641:Ammonia / Q000096:biosynthesis*; D000818:Animals; D002118:Calcium / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D005973:Glutamine / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D000316:Adrenergic alpha-Agonists; D005973:Glutamine; D010656:Phenylephrine; D000641:Ammonia; D002118:Calcium; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine