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A E Domínguez

Publications and source records attributed to A E Domínguez.

15 recordsLinked to original sources
PubMed1991

Angiotensin II increases MAO activity in rat central nervous system.

The effects of angiotensin II (ANG II) and bilateral nephrectomy on monoamine oxidase (MAO) activity were studied in rat hypothalamus and medulla oblongata. ANG II increased MAO activity in both central nervous system (CNS) regions. The fall of circulating ANG II caused by 48 h bilateral nephrectomy decreased the activity of the enzyme in the mentioned areas. The results showed that ANG II stimulates catecholamine metabolism in the CNS.

Angiotensin II↗
PubMed1983

Contrasting effect of verapamil on catecholamine release induced by acetylcholine and by NaCl-omission from the bovine adrenal medulla.

Verapamil (3 X 10(-4) M) produced a 92.2% inhibition on the release of catecholamines induced by acetylcholine in perfused bovine adrenal glands. This blocking effect was slowly reversible. On the other hand, verapamil (3 X 10(-4) M) failed to antagonize the secretory response evoked by the substitution of NaCl by sucrose in the perfusion fluid. A similar lack of inhibitory effect of verapamil on catecholamine output produced by NaCl-omission was observed in the absence of extra-cellular Ca2+. These results suggest that Ca2+ influx might not be involved in adreno-medullary secretion induced by the substitution of NaCl by sucrose in the perfusion medium.

Acetylcholine↗
PubMed1983

[The renin-angiotensin system and noradrenaline release in the hypothalamus and medulla oblongata].

The effect of angiotensin II (AII) and 48 h bilateral nephrectomy on the 3H-norepinephrine (3H-NE) and 3H-NE metabolites release in vitro was studied in slices of male Wistar rat hypothalamus and medulla oblongata. The total 3H outflow of radioactivity was higher in AII exposed tissues than in nephrectomized ones of both organs. The 3H-NE and 3H-NE metabolites remanent radioactivity in the tissues increased in both the soluble cytoplasmatic fractions and the granular vesicle ones, in the two organs from the nephrectomized rats. The ratio between granular and cytoplasmatic NE and granular and cytoplasmatic radioactive metabolites was not noticeably altered in any of the groups. The release of 3H-NE caused by AII and the opposite effect by nephrectomy, agree with the inverse relationship demonstrated between endogenous NE content in the central nervous system and AII plasmatic levels. AII might act on presynaptic NE receptors of the cellular membrane. The relationship between the renin-AII system and the central nervous system catecholamines could be involved in the control of development and maintenance of the renal arterial hypertension.

Angiotensin II↗
PubMed1982

Angiotensin II-norepinephrine relationship in the central nervous system.

The effects of angiotensin II (AII) and bilateral nephrectomy on [3H] norepinephrine (NE) uptake in hypothalamus and medulla oblongata were studied in male rats. The endogenous NE content in hypothalamus increased 4, 24 and 48 h after nephrectomy with a simultaneous decreasing of plasma renin activity. Intraventricularly infused [3H] NE uptake increased in hypothalamus and medulla oblongata of nephrectomized animals in cytoplasmatic compartment as in granular stores, while it decreased in hypothalamus of AII-infused animals. [3H] NE metabolites radioactivity decreased in nephrectomized animals if they are compared with AII-infused ones. These changes were independent of systolic arterial pressure that was not modified in none of the groups. The study of the ratio granular/cytoplasmatic [3H] NE and metabolites radioactivity shows that AII probably acts on cellular membrane uptake of NE. The modification of metabolites/NE ratio in both stores would be due to AII action on MAO activity. The effects of AII and nephrectomy on [3H] NE uptake can explain the inverse relationship between circulating AII levels and NE content in the central nervous system (CNS).

Angiotensin II↗
PubMed1981

Characteristics of the arterial hypertension by subtotal nephrectomy in the rat.

The importance of the hemodynamic parameters in the hypertensive rats by subtotal nephrectomy and the role of the neurogenic tone in the maintenance of high blood pressure were studied. The baroreceptor sensitivity is significantly diminished in the hypertensive rats with respect to normal ones. The resistance of the hindquarters to perfusion with constant flows was decreased in the hypertensive animals. No differences were observed in the arterial pressure, cardiac output, heart rate, stroke volume and peripheral resistance between both groups of anesthetized animals. The pressure response to the phenylephrine injection was higher in the conscious hypertensive animals than in the normotensive rats but it was the same after the anesthesia and the blocking of ganglionic transmission. These results suggest that an increment of the neurogenic tone exists in the chronic phase of hypertension in this experimental model and it could be responsible for the elevated blood pressure.

Animals↗
PubMed1978

Saralasin and SQ 20881 : their effects on central nervous system norepinephrine.

The effects of the infusion of Saralasin and SQ 20881, two drugs that inhibit the renin-angiotensin system, on the norepinephrine (NE) concentration in hypothalamus and medulla oblongata were studied in male Wistar rats. NE content increased in hypothalamus in response to both drugs, without changes in medulla oblongata catecholamine concentration. These results showed that the NE concentration of certain areas of the central nervous system can be modified, in a short time, by the inhibition of the renin-angiotensin system. Results observed after the infusion of Saralasin could indicate that the receptors, on which the angiotensin acts to produce this alteration, are similar to those of the peripheral blood vessels.

Angiotensin II↗
PubMed1977

Modifications of arterial pressure and plasma renin: their effects on the norepinephrine content of hypothalamus and medulla oblongata.

The effects of the bilateral nephrectomy and acute hypotension caused by the cava vein ligature on the norepinephrine (NE) concentration in hypothalamus and medulla oblongata and on the plasma renin activity were studied in male rats. NE increased and plasma renin activity decreased in hypothalamus in 24 h nephrectomized rats with or without the ligatures of the cava vein. NE also decreased in medulla of groups with the ligatures only. The mean arterial pressure, did not correlate with the NE or plasma renin activity levels. The modifications of the NE in the central nervous system showed an inverse relationship with plasma renin activity and this, could be due to changes in the NE uptake and/or release caused by the plasma renin activity alterations. NE modifications do not seem to be caused directly through reflex of the arterial pressure.

Animals↗
PubMed1975

[Action of the sexual hormones on the endogenous norepinephrine of the central nervous system (author's transl)].

The effects of ovariectomy and the injection of sexual hormones on the norepinephrine (NE) content in different areas of the central nervous system were studied in the Wistar female rat. The ovariectomy increased the NE in the hypothalamus, cerebellum and the medulla oblongata. The estradiol benzoate did not modify the NE levels in the ovariectomized rats. Progesterone decreased the NE in the hypothalamus and testosterone dipropionate increased it in the brain hemispheres. It seems possible that the hypersecretion of FSH would increase the synthesis of NE in castrated animals through the potentation of the tyroxine-hydroxylase activity. Increase in testosterone synthesis was probably responsible for the raise in NE levels. The progesterone moderated the effects of the ovariectomy, probably through feed-back mechanisms involving the hypothalamic-hypophyseal tract.

Animals↗
PubMedDate not supplied

Atrial natriuretic peptide and angiotensin II interaction on noradrenaline uptake in the central nervous system.

The effects of different concentrations of atrial natriuretic peptide and angiotensin II on [3H]-noradrenaline uptake in hypothalamus and medulla oblongata slices incubated in vitro were determined. Atrial natriuretic peptide, in a dose of 100 mM, increased [3H]-noradrenaline uptake in both regions, while 1 microM of angiotensin II had the opposite effect. The ineffective concentration of 1 nM atrial natriuretic peptide reversed the action of 1 microM of angiotensin II on [3H]-noradrenaline uptake, whereas ineffective concentrations of angiotensin II failed to modify atrial natriuretic peptide effects. These results are compatible with the existence of an atrial natriuretic peptide-angiotensin II interaction in the central nervous system and with the hypothesis that some of the hypotensive effects of atrial natriuretic peptide could occur through modulation of an angiotensin-noradrenergic mechanism in the central nervous system.

Angiotensin II↗