Evidence for an extraneuronal location of monoamine oxidase in renal tissues.
(1) Homogenates of renal cortex and renal medulla of control and 6-hydroxydopamine-denervated cat kidneys were prepared. (2) Monoamine oxidase (MAO) activity was determined with [3H]-5-hydroxytryptamine [( 3H]-5HT) and [14C]-beta-phenylethylamine [( 14C]-beta-PEA) as preferential substrates for MAO-A and MAO-B, respectively. (3) The endogenous dopamine and noradrenaline tissue contents of control and chemically-denervated kidneys were compared with the MAO activities. (4) The results show that a 70% depletion of monoamine content by chemical denervation resulted only in a 23% reduction of MAO-A activity in the renal cortex, whereas MAO-B was unaffected either in the cortical or the medullary zones; in the renal medulla MAO-A activity was not changed by denervation. Most of the MAO activity in the cat kidney is of the B type (74%) and is located in the renal cortex.
Caramona
M M
MM
Laboratório de Farmacologia, Faculdade de Medicina, Porto, Portugal.
Soares-da-Silva
P
P
D000818:Animals; D002415:Cats; D004298:Dopamine / Q000378:metabolism; D005110:Extracellular Space / Q000201:enzymology*; D007527:Isoenzymes / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology* / Q000294:innervation; D007672:Kidney Cortex / Q000201:enzymology; D007679:Kidney Medulla / Q000201:enzymology; D008995:Monoamine Oxidase / Q000378:metabolism*; D009474:Neurons / Q000201:enzymology*; D009638:Norepinephrine / Q000378:metabolism
D007527:Isoenzymes; D008995:Monoamine Oxidase; D004298:Dopamine; D009638:Norepinephrine