Search PubMed⌕ Search

Biomedical subjects

E Ikonomu

Publications and source records attributed to E Ikonomu.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effects of extracellular fluid volume changes on renal response to low-dose dopamine infusion in normal women.

Dopamine (DA) i.v. infused in a low dose (0.1 microgram/kg/min) in healthy women during sustained hypotonic polyuria, produced different renal functional effects as variations in extracellular fluid volume occurred. (1) In hydro-saline retention (n = 23), induced by desoxycorticosterone acetate treatment, DA produced typical vasodilator and hydro-natriuretic effects (Goldberg, 1972). (2) In hydro-saline depletion (n = 19), induced by diuretic treatment and low dietary sodium intake, DA lost its vasodilator and natriuretic efficacy, manifesting, on the other hand, renal sodium conserving effects mainly dependent on the increase in distal sodium reabsorption and a trend towards afferent arteriolar vasoconstriction. (3) Treatment with prazosin (n = 9) or propranolol (n = 9) in hydro-saline depletion, was efficacious in partly restoring the typical vasodilator and natriuretic effects of DA. Thus, in hydro-saline depletion, DA produced sympathomimetic effects which were sufficiently intense to outweigh those due to activation of specific DA renal receptors.

Adult↗
PubMed1984

[Low-dose dopamine as an activator of renal catecholamine receptors of different classes. I. Studies in water-salt depletion].

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↗