Determination of 3-hydroxytyramine and dopa in various organs of dog after dopa-infusion

Wegmann, A

doi:10.1007/bf00245004

Cited by 11 publications

(6 citation statements)

References 6 publications

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“…Dopa is probably an inert compound (16)(17)(18), which, when infused, increases the renal content of dopamine (5)(6)(7). In intact dogs, renal artery infusions of dopa were phosphaturic.…”

Section: Discussionmentioning

confidence: 99%

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Phosphaturic effect of dopamine in dogs. Possible role of intrarenally produced dopamine in phosphate regulation.

Cuche¹,

Marchand²,

Greger³

et al. 1976

J. Clin. Invest.

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A B S T R A C T A possible role for dopamine in phosphate handling by the dog kidney was investigated by intrarenal artery infusions of dopamine. Dopamine increased fractional phosphate excretion both in the presence and absence of control of parathyroid hormone and calcitonin. In addition, dopamine increased both renal blood flow and sodium excretion; however, the phosphaturia was independent of these changes; since 30 min after completion of dopamine infusion, renal blood flow and sodium excretion returned to control levels and phosphate excretion remained elevated. For comparison, the vasodilator isoproterenol increased renal blood flow and sodium excretion without a significant change in fractional phosphate excretion. Thus, the phosphaturic effect of dopamine is probably independent of its vasodilator effect. The phosphaturic effect of dopamine could not be accounted for by subsequent conversion to norepinephrine, since norepinephrine was antiphosphaturic in the dog.The effect of endogenous dopamine on renal phosphate excretion was investigated by intrarenal infusion of the precursor dopa. Dopa was phosphaturic both in the presence and absence of parathyroid hormone and calcitonin. In dogs pretreated with carbidopa, which blocks conversion of dopa to dopamine, dopa was no longer phosphaturic, although the kidney remained responsive to dopamine. It is postulated that dopamine may play a role in the intrarenal regulation of phosphate excretion.

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“…Dopa is probably an inert compound (16)(17)(18), which, when infused, increases the renal content of dopamine (5)(6)(7). In intact dogs, renal artery infusions of dopa were phosphaturic.…”

Section: Discussionmentioning

confidence: 99%

“…This enzyme system may account in part for the increased renal dopaminie content during dopa infusions in dogs and rats (5)(6)(7). Therefore, we hypothesized that endogenous dopamine, i.e., intrarenally produced dopamine, might also have a role in renal phosphate handling.…”

Section: Introductionmentioning

confidence: 99%

Phosphaturic effect of dopamine in dogs. Possible role of intrarenally produced dopamine in phosphate regulation.

Cuche¹,

Marchand²,

Greger³

et al. 1976

J. Clin. Invest.

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“…Dopa is metabolized rapidly after intravenous infusion, allowing for pulse labeling of tissue catecholamines, whereas the dietary precursor, tyrosine, persists in tissues for long periods after administration (12). Unlike norepinephrine (13) and dopamine (14), L-dopa readily penetrates the blood brain barrier (14) and nonspecifically enters sympathetic neurones (15,16) where it is converted to the neurotransmitter substance, L-norepinephrine. Thus, endogenous labeling of norepinephrine from dopa_3H occurs by a more physiologic route.…”

Section: Introductionmentioning

confidence: 99%

Catecholamine turnover in normotensive and hypertensive man: effects of antiadrenergic drugs

DeQuattro¹,

Sjoerdsma²

1968

J. Clin. Invest.

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A B S T R A C T Intravenous administration of tritium-labeled 3,4-dihydroxyphenylalanine (dopa) to human subjects resulted in the labeling of endogenous catecholamines and vanillylmandelic acid (VMA). Determination of the changes in specific activity of these compounds with time in fractional collections of urine and in cardiac biopsies from patients undergoing corrective cardiac surgery permitted estimation of apparent turnover rates. The average half-time of the exponential decline in specific activity of labeled urinary norepinephrine was about 8 hr and that of VMA was 11-16 hr in five normal subjects. No significant differences from normal were observed in eight patients with essential hypertension. The average half-life of norepinephrine was only 5 hr in cardiac patients undergoing surgery, and the levels and rate of decline of cardiac norepinephrine specific activity correlated well with the exponential phase of the urinary disappearance curve. There were significant effects of treatment with alpha-methyltyrosine, reserpine, and pargyline hydrochloride on the labeling and apparent turnover rates of norepinephrine and VMA; the effects noted were consistent with known actions of these three drugs. It is suggested that the technique used is a suitable means of assessing "over-all" catecholamine metabolism in man, particulary if combined with

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“…The kidney has been shown to possess an aromatic amino acid decarboxylase capable of forming dopamine [3,9,20,25,27,33]. If the observation of the present study can be extrapolated, they would suggest that locally formed dopamine in the kidney may be capable of inhibiting water transport.…”

Section: Discussionmentioning

confidence: 48%

“…It remains uncertain whether these effects of d o p a m i n e in vivo result from a direct effect of the drug on transport processes or is the result of h e m o d y n a m i c alterations caused by the neurotransmitter [14]. It has been d e m o n s t r a t e d that dop a m i n e may be formed locally in the kidney by an aromatic a m i n o acid decarboxylase which is present in large a m o u n t s in the kidney [3,9,20,25,33]; d o p a m i n e could thus serve as a local m o d u l a t o r of certain transport processes.…”

Section: Introductionmentioning

confidence: 99%

Dopaminergic inhibition of vasopressin-stimulated water flow in the toad bladder: Evidence for local formation of dopamine

Arruda

Sabatini

1982

J. Membrain Biol.

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Dopamine administration increases renal excretion of water and Na. It remains uncertain whether these effects of dopamine are the result of a hemodynamic effect or the consequence of a direct cellular action. We investigated the effect of dopamine on water transport by the isolated toad bladder in vitro. Dopamine failed to alter baseline water flow but caused a significant inhibition of arginine vasopressin (AVP) or cyclic adenosine monophosphate (AMP) stimulated water flow. The effect of dopamine on stimulated water flow was not due to activation of c~ adrenergic, /~ adrenergic, or cholinergic receptors. The selective antagonists of dopamine, metoclopramide and apomorphine, prevented the effect of dopamine on AVP-stimulated water flow. These observations suggest the existence of a dopaminergic receptor in the toad bladder. L-Dopa also inhibited AVP-stimulated water flow. The effect of L-Dopa could be prevented by metoclopramide, thus suggesting that L-Dopa is converted to dopamine by an aromatic amino acid decarboxylase present in the toad bladder. To investigate this possibility we measured the effect of the decarboxylase inhibitor, carbidopa, on the 14C02 production generated by decarboxylation of 14C L-Dopa in isolated toad bladder epithelial cells. Isolated toad bladder epithelial cells generated significant amounts of 14C0z from 14C L-Dopa. This effect could be blocked by carbidopa, thus suggesting the existence of an aromatic amino acid decarboxylase system in the toad bladder. Carbidopa also prevented the inhibitory effect of L-Dopa on AVP-stimnlated water flow, suggesting that L-Dopa needs to be converted to dopamine to inhibit water flow. These data suggest the existence of a dopaminergic receptor in the toad bladder. These data also suggest that dopamine can be formed locally in the toad bladder and can thus serve as a local modulator of water transport.

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Determination of 3-hydroxytyramine and dopa in various organs of dog after dopa-infusion

Cited by 11 publications

References 6 publications

Phosphaturic effect of dopamine in dogs. Possible role of intrarenally produced dopamine in phosphate regulation.

Phosphaturic effect of dopamine in dogs. Possible role of intrarenally produced dopamine in phosphate regulation.

Catecholamine turnover in normotensive and hypertensive man: effects of antiadrenergic drugs

Dopaminergic inhibition of vasopressin-stimulated water flow in the toad bladder: Evidence for local formation of dopamine

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