Dopamine and Hypertension

Yoshimura, Manabu; Takahashi, Hakuo

doi:10.1007/978-1-349-09503-2_6

Cited by 9 publications

(4 citation statements)

References 23 publications

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“…The results presented here show that a substantial amount of newly-formed dopamine is deaminated to DOPAC; this occurs largely in the renal cortex where saturation of deamination of dopamine could be observed, but also to some extent in the medulla and this difference may be related to the limited production of dopamine in the rat renal medulla. Alternatively, it could be hypothesized that in the rat renal medulla the specific activity of MAO may exceed that in the renal cortex, as has been found to occur in the kidney of the cat (Caramona & Soares-daSilva, 1990 In recent years, several lines of evidence have suggested that dopamine may exert considerable effects within the kidney and contribute actively in the maintenance of blood pressure at levels considered as acceptable (Lee, 1982;Yoshimura & Takahashi, 1988;Bertorello et al, 1988). The activation of -I type D1 dopamine receptors in the renal vasculature produced vasodilatation resulting in increased renal blood flow and glomerular filtration rate (Felder et al, 1988).…”

Section: Discussionmentioning

confidence: 97%

“…In recent years, several lines of evidence have suggested that dopamine may exert considerable effects within the kidney and contribute actively in the maintenance of blood pressure at levels considered as acceptable (Lee, 1982;Yoshimura & Takahashi, 1988;Bertorello et al, 1988). The activation of -I type D1 dopamine receptors in the renal vasculature produced vasodilatation resulting in increased renal blood flow and glomerular filtration rate (Felder et al, 1988).…”

Section: Discussionmentioning

confidence: 99%

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Deamination of newly‐formed dopamine in rat renal tissues

Fernandes

Pestana

Soares-da-Silva

1991

British J Pharmacology

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1 The present study has examined the formation of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) in slices of the rat renal cortex and the renal medulla loaded with exogenous L-fl-3,4-dihydroxyphenylalanine (L-DOPA). The effects of pargyline and of two selective inhibitors of monoamine oxidase (MAO) types A and B, respectively Ro 41-1049 and Ro 19-6327, on the deamination of newlysynthesized dopamine in kidney slices incubated with exogenous L-DOPA were also tested. The assay of L-DOPA, dopamine, noradrenaline and DOPAC was performed by means of h.p.l.c. with electrochemical detection. 2 Incubation of renal slices with exogenous L-DOPA resulted in a concentration-dependent accumulation of dopamine and DOPAC; the tissue levels of newly-formed dopamine and DOPAC in slices of the renal medulla were 6-8% of those in cortical slices. 3 Pargyline (0.1 mM) produced a marked decrease (84% reduction) in the formation of DOPAC in kidney slices loaded with 1.0mM L-DOPA; this effect was accompanied by a 17% increase in the accumulation of dopamine. Similar effects were obtained at higher concentrations of pargyline (0.5 and 1.0mM). At 5.0 and 10.0mm pargyline, a marked decrease (46 and 76% reduction) in the accumulation of newlyformed dopamine was observed. 4 The accumulation of dopamine and DOPAC was found to be time-dependent in experiments in which tissues were incubated with 5 and 1IOPM L-DOPA for 5, 10, 20 and 30min. Pargyline (0.1 mM) produced an increase in the accumulation of dopamine at all incubation periods and decreased the formation of DOPAC. 5Ro 41-1049 (50, 100 and 250 nM) was found to produce a concentration-dependent increase of newlyformed dopamine (16-66% increase) and reduced DOPAC formation (44-89% reduction). Ro 19-6327 (50, 100 and 250nM), was found not to affect the accumulation of newly-formed dopamine, but significantly reduced the formation of DOPAC. 6 It is concluded that deamination of newly-formed dopamine in kidney slices loaded with L-DOPA constitutes an important mechanism of amine inactivation. The results presented also suggest that most of the MAO, located inside the compartment where the synthesis of dopamine occurs, is of the A type.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Deamination of newly‐formed dopamine in rat renal tissues

Fernandes

Pestana

Soares-da-Silva

1991

British J Pharmacology

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“…There are conflicting reports (3,4,6,(19)(20)(21)(22) on plasma and urinary DA concentrations in patients with essential hypertension. Some studies have demonstrated that plasma or urinary excreted DA is enhanced in patients with borderline or early stage of essential hypertension (19).…”

Section: Da and Essential Hypertensionmentioning

confidence: 99%

“…Some studies have demonstrated that plasma or urinary excreted DA is enhanced in patients with borderline or early stage of essential hypertension (19). However the DA concentrations in tends to decrease with advancing stages of hypertension (20). Therefore, the dopaminergic activity changes with different stages of hypertension.…”

Section: Da and Essential Hypertensionmentioning

confidence: 99%

Diagnostic Significance of Dopamine Estimation Using Plasma and Urine in Patients with Adrenal and Renal Insufficiency, Renal Transplantation and Hypertension

Yoshimura¹,

Komori²,

Nishimura³

et al. 1995

Hypertens Res

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Although free and conjugated dopamine (DA) constitute most of the plasma and urine catecholamine pool, the diagnostic significance of DA estimation for the evaluation of illness is not clear. We evaluated the clinical utility of DA estimation by measuring free and conjugated DA in patients with various illness. Patients with adrenal insufficiency did not show decreases in DA concentrations but did demonstrate reductions in free and conjugated plasma adrenaline (Ad). Patients with established stage of essential hypertension exhibited decreased plasma concentrations of free and conjugated DA, although they were hyperadrenergic. In patients with chronic renal insufficiency and failure, the free DA concentration in the urine decreased depending on the severity of renal impairment. Conversely, plasma concentrations of conjugated DA are higher in patients with chronic renal failure than in normal subjects. The high plasma concentrations of conjugated DA decreased dramatically following hemodialysis and renal transplantation. Urinary free DA excretion increased markedly following renal transplantation. In conclusion, the estimation of the free and conjugated DA in plasma and urine is clinically useful for the diagnosis of adrenal insufficiency, essential hypertension, and renal insufficiency and failure. It also can be used to monitor the effectiveness of hemodialysis and renal transplantation. (Hypertens Res 1995; 18 Suppl. I: S87-S92) Key Words: free dopamine, conjugated dopamine, adrenal insufficiency, essential hypertension, renal transplantationWe have developed methods to measure free and conjugated catecholamines in clinical samples as a routine laboratory exam using HPLC and have tried to estimate the clinical utility of free and conjugated dopamine (DA) as a diagnostic aid (1). Previous investigators (2-7) have reported trace amounts of free DA in the plasma in various illness, but the values of free DA were variable in each study. Some studies (2-4) have reported relatively low free DA concentrations in the plasma, near the detection limits of the assay, while other studies (5, 6) have found relatively high concentrations of free DA in the plasma. Similarly, the plasma concentrations of conjugated DA were variable (2-7). We have already reported the wide individual variations and circadian rhythm of free and conjugated DA concentrations in healthy volunteers (8).The total DA, including the free and conjugated forms constitutes the majority (approximately 60-70%) of total circulating catecholamines including DA, noradrenaline (NA) and adrenaline (Ad) (Fig. 1). The physiological and pathological roles of plasma free NA and Ad are well-known. Although large amounts of DA exist in the circulation, the pathophysiological roles of free and conjugated DA are not clear. Moreover, it has been reported that conjugated DA can be converted directly into free DA,. Therefore, it is important to measure the free and conjugated DA independently when evaluating the pathophysiological significance of DA in the plasma. Although...

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