The renal function in healthy man with salt and water depletion induced by natriuretic treatment was explored during steady hypotonic polyuria. Four 15 min clearance (cl.) periods, before, during and after dopamine (DA) infusion in a subpressor dose were performed. The 12 examined subjects showed different renal hemodynamic responses in the early stage of DA infusion, i.e. hyperemic (4 subjects, subgroup A) or ischemic (8 subjects, subgroup B). A decrease in urinary sodium excretion and increase in tubular sodium reabsorption, in particular at the diluting segment level, were induced by DA in both subgroups, at least in the late stage of infusion. During the control cl. period in subgroup A as compared with B the renal plasma flow was lower and the tubular sodium reabsorption higher, suggesting a relatively higher level of renal adrenergic activity.

Dopamine↗

PubMed1984

[Low-dose dopamine as an activator of renal catecholamine receptors of different classes. II. Studies in water-saline depletion and associated adrenergic blockade].

The renal function in healthy man with salt and water depletion (natriuretic pretreatment) associated with adrenergic blocking agents administration was explored during steady hypotonic polyuria. Four 15 min clearance (cl.) periods, before, during and after dopamine (DA) infusion in a subpressor dose, were performed. The 9 subjects treated with prazosin showed different renal hemodynamic responses in the early stage of DA infusion i.e. hyperemic (6 subjects, subgroup A) or ischemic (3 subjects, subgroup B). The whole group of 6 subjects treated with propranolol showed an hyperemic response DA infusion. A natriuretic effect and a trend towards tubular sodium reabsorption inhibition, in particular at the diluting segment level, were associated with the DA vasodilatory responses. The ischemic responses to DA occurred in the presence of incomplete alpha-adrenergic receptors blockade; nevertheless in the same circumstances DA failed to increase the diluting segment sodium reabsorption.

Dopamine↗

PubMed1984

[Relation between acute changes in diuresis and renal prostaglandins. I: Induced hypotonic polyuria].

We have evaluated the effects of indomethacin (I) and of a rich in linoleic acid phosphatidylcholine (E) on the renal function and on the PGE urinary excretion during steady hypotonic polyuria. 5 normal subjects have been studied in the absence of treatment (TA) and after treatment with I, E, E + I. The renal function has been estimated by clearance (cl.) method during hypotonic polyuria induced by oral water loading and i.v. infusion of 5% dextrose solution. The glomerular filtration rate has been estimated by cl. of endogenous creatinine; moreover have been measured the osmotic clearances (Cosm, CH2O), the sodium and potassium clearances (CNa, CK), the mean arterial pressure (PA) and the urinary prostaglandins of E series (PGE) by RIA method. In I condition is observed: a) a trend to a glomerular filtration rate decrement; b) a significant decline of the urinary flow rate, CH2O, UPGV and a significant increment of the urinary osmolarity; c) a trend to an increment of potassium and a decrement of sodium urinary excretions; d) a significant increase of PA. It is possible that the contrary effects observed during the hypotonic polyuria in E condition depend on the stimulating effects of this material on the PG intrarenal synthesis.

Adult↗

PubMed1984

[Relation between acute changes in diuresis and renal prostaglandins. II. Induced antidiuresis].

We have evaluated the effects of indomethacin (I) and of a rich in linoleic acid phosphatidylcholine (E) on the renal function during in bolo infusion of lysine-8-vasopressin (LVP). 5 normal subjects have been studied in the absence of treatment (TA) and after treatment with I, E, E+I respectively. Two clearance (cl.) periods have been performed in the following time intervals: 0-30 min and 30-60 min after in bolo LVP (1.5 m-U.kg-1) infusion. Have been measured: the urinary flow rate, V, the endogenous creatinine cl., Cc, the osmotic clearances, Cosm, CH2O, the sodium and potassium cl., CNa, CK, the urinary prostaglandins (PG) of E series excretion (UPGV) by RIA method and the mean of arterial pressure (PA). 1) In TA condition LVP decreases V, Cosm, Cc, CH2O, CNa, CK and slightly increases the urinary osmolarity; these effects regress during the interval 30-60 min. 2) In I condition LVP produces a significant increment of PA and prolonged and intensified decrement of Cc, CH2O, V; in this condition the increase of urinary osmolarity is greater than in TA condition. 3) The E-treatment alone does not affect the LVP-induced renal effects; however the enhancement of these effects produced by I is attenuated in the presence of E though UPGV does not differ in I and E+I.

Creatinine↗

PubMed1984

[Sulpiride (stereoisomers, racemic) and dopamine: actions and interactions on renal circulation].

Interaction of sulpiride - both 1- and d- isomers as well as racemic- - with Dopamine (DA, subpressor dosage 0.1 microgram X kg -1 X min -1), on the renal hemodynamic, was studied in DOCA-pretreated men during hypotonic polyuria. P.A.H. and creatinine clearance and renal vascular resistances were determined. In the presence of d-Sulpiride, DA - induced renal vasodilation is carried out gradually and finally reaches similar levels as in the absence of d-Sulpiride. However no glomerular filtration rate increase is produced by DA. In the presence of 1-Sulpiride, DA vasodilating effect is suppressed. On the contrary a trend toward ischemia and a reduction in glomerular filtration rate becomes finally apparent. Stronger binding of 1- than d-Sulpiride with vascular DA receptors in suggested. When both isomers are simultaneously administered (at the nearly total dosage) much less inhibitory effect on DA vasodilator action is observed: it seems that each isomer decreases the affinity on the other isomer for vascular DA receptors.

Desoxycorticosterone↗

PubMed1984

[Sulpiride (stereoisomers, racemic) and dopamine: actions and interactions on tubular reabsorption].

In DOCA-pretreated men during hypotonic polyuria Dopamine (DA) infusion in a subpressor dosage (0.1 microgram X kg -1 X min -1) produces renal hyperemia, inhibition of isosmotic sodium reabsorption, increase in sodium distal load (s. d.l.) and finally inhibition of anisosmotic sodium reabsorption as a percentage of s.d.l. Such DA effects are variously modified by sulpiride isomers. Sodium distal load increase is still apparent in the presence of racemic, but not in the presence of either d- or l-Sulpiride isomers. However DA inhibition of anisosmotic sodium reabsorption % s.d.l. is unaffected by either or both Sulpiride isomers. If the DA tubular inhibition was dependent on specific DA receptors these receptors, unlike vascular DA receptors, would bind in a weaker way both d- and l-Sulpiride isomers.

Absorption↗

PubMed1984

[Sulpiride (stereoisomers, racemic) and dopamine: actions and interactions on renal excretion of hydro-saline].

Renal effects of Dopamine (DA, subpressor dosage 0.1 microgram X kg -1 X min -1) during hypotonic polyuria in moderate hydro-saline retention are variously modified by either d- or l-Sulpiride isomers. In the presence of d-Sulpiride, DA effects, such as an increase in diuresis, free water clearance (CH20) and kaliuresis are suppressed, while increases of saluresis and natriuresis are significantly blunted. In the presence of l-Sulpiride no changes are observed in both saluresis and natriuresis, while decreases occur in diuresis, CH20 and kaliuresis. The inhibitory DA effects on isosmotic sodium reabsorption as a percentage of sodium filtered load are prevented by either isomer as well. A possible role of ineffective renal vascular DA action can be involved in such defective tubular inhibition. However is also suggested a pharmacological blockade of proximal tubular specific DA receptors.

Body Water↗

PubMed1983

[Catecholamine receptors and renal function].

Renal function was assessed through clearance studies in man under initial conditions marked by retention (23 experiments) and hydro-saline depletion (19 experiments). Further evaluations were carried out in depletion combined with treatment with (+/-)-propranolol (9 experiments) or with prazosin (9 experiments). In each study, clearance was checked during and after venous infusion of 0.1 micrograms/kg-1/min-1 DA, in addition to the control clearance. Adrenolytic drugs and renal function in hydro-saline depletion. Combination with propranolol had no significant effect on renal function, whereas prazosin led to a significant increase in both total and afferent renal vascular resistance; the flow rate and filtrate were less despite higher arterial pressure. Both the absolute and the percentage loading value of isosmotic and anisosmotic sodium reabsorption were inhibited. Renal action of DA in depletion with and without adrenolytic drugs. DA failed to produce either vasodilatation or a hydro-natriuretic effect during hydro-saline depletion, by contrast with its effect at the same dose during retention. During its infusion, however, it led to sodium saving dependent on stimulation of distal sodium reabsorption; following suspension, this saving increased still further, and there was a significant decrease in flow rate, filtrate and diuresis. Pretreatment with either drug restored the vasodilatatory and hydrosaluretic capacity of DA. Modalities whereby renal function is controlled in the presence of changes in body water and salt content. 1) During retention and during depletion in association with prazosin, anisosmotic transport of sodium is efficient in inverse proportion to the sodium load reaching the diluting segments. Prazosin depresses reabsorption efficiency in the presence of load values similar to those observed during simple depletion. 2) During retention, urinary sodium naturally depends on plasma osmolarity, whereas blood sodium appears to depend on urinary excretion of sodium. During depletion, renal excretion apparently depends on mean blood pressure. These extra-renal control mechanisms probably result in alteration of one or more of the components of the direct line running from the filtrate to the formation urine. 3) When DA is infused during water-salt retention, renal excretory function can be seen to depend on the glomerular filtrate through direct control of diuresis. During depletion in the early stage of DA infusion, on the other hand, the filtrate depends on excretory function through tubulo glomerular feedback control.

Adult↗

PubMed1983

[Effects of acute changes in water balance on hydrosaluresis and on urinary excretion of prostaglandin E, in the presence and absence of a cyclooxygenase inhibitor].

Five healthy females were studied in order to evaluate the effects of a cyclo-oxygenase inhibitor agent (Indomethacin, I) on the hydro-saluresis and urinary excretion of prostaglandins (PG) of E series. Each subject was studied during both hypotonic polyuria (oral water load) and hypertonic olyguria (18 h water intake withheld). 1) In water diuresis I. treatment significantly (P less than 0.05) decreased urinary flow (36%) as well as sodium and potassium excretions (32%, 46%, respectively); the rise in urinary osmolarity (86%) and the fall in PGE excretion (63%) were statistically insignificant. 2) In antidiuresis I. treatment significantly (P less than 0.05) decreased urinary flow (50%) as well as sodium, potassium and PGE excretions (55%, 45%, 85%, respectively); furthermore urinary osmolarity was increased (26%, P less than 0.01). If I. renal effects are mediated by PG biosynthesis inhibition, the above data are consistent with an involvement of PG in hydrosaluresis control (at least in our experimental conditions).

Diuresis↗

PubMed1983

[Renal function during water-salt depletion. Effects of alpha-blocking treatment with prazosin].

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Adrenergic alpha-Antagonists↗