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Biomedical subjects

G B Picotti

Publications and source records attributed to G B Picotti.

At least 55 records · Page 3Linked to original sources
PubMed1983

Effects of light saline loading on renal renin and catecholamine release in hypertensive humans.

In 8 essential hypertensive patients infusion of 7.5 ml kg-1 b.w. of isotonic saline over 20 min decreased plasma renin activity but did not affect plasma adrenaline or noradrenaline concentrations in suprarenal aortic, renal venous and caval blood. Mean blood pressures and heart rates were unchanged throughout the saline infusion period, whereas the hematocrit was significantly decreased. These data suggest that inhibition of renin secretion after slight volume expansion with saline in hypertensive humans occurs without parallel inhibition of either renal neurosympathetic drive or humoral adrenergic tone to the kidney through circulating catecholamines.

Adult↗
PubMed1983

Different rebound rise in plasma prolactin during the postdopamine infusion phase in puerperal women and patients with pathological hyperprolactinemia.

Dopamine infused at a rate of 4 micrograms/kg . min for 120 min induced at the end of the infusion period a clear-cut and similar suppression of circulating PRL levels in normal and puerperal women as well as in patients with hyperprolactinemia either due to a tumor or of unknown etiology. At the discontinuation of the infusion there was a marked PRL rebound above baseline levels in normal subjects and a rapid return to basal levels in subjects with pathological hyperprolactinemia. In contrast, there was no increase in plasma PRL in puerperal women, in whom PRL levels remained suppressed during the whole postinfusion period. The reason(s) for this pattern in puerperal women is presently unknown, although previous estrogen loading of the lactotropes during pregnancy may be involved.

Adolescent↗
PubMed1983

[Hermansky-Pudlak syndrome in a Valais village].

Amongst 13 subjects with albinism observed in a village in the Valais, 7 present the clinical and laboratory findings of the Hermansky-Pudlak syndrome. Because of the close family links and the numerous consanguine marriages present in the pedigree, it is probable that the 5 subjects who could not be examined also suffer from the same syndrome. It has an autosomal recessive mode of inheritance. In this isolate the gene and heterozygote frequencies are, respectively, 1:12 and 1:6. Clinically the hemorrhagic diathesis is moderate, the visual and cutaneous symptoms predominate. The platelet dysfunction results from a lack of storage of components (Ca++, nucleotides, amines) normally present in the dense granules. The lack of dense granules is demonstrated by electron and fluorescence microscopy. This structural anomaly is present in the megacaryocyte before individualization of the platelets. Giant melanosomes were found in skin melanocytes.

Abnormalities, Multiple↗
PubMed1982

Plasma catecholamine concentrations in normotensive rats of different strains and in spontaneously hypertensive rats under basal conditions and during cold exposure.

Under basal conditions, the levels of circulating norepinephrine (NE) and epinephrine (E) were higher in normotensive Wistar rats of different origins than in Sprague-Dawley rats. Since the decline of 3H-NE concentration in the plasma after i.v. injection was similar in Wistar and in Sprague-Dawley rats, the higher levels of endogenous NE in the former strain probably reflect greater NE release from sympathetic nerve terminals. In normotensive Sprague-Dawley and Wistar rats, plasma NE rose to various extents during cold exposure (4 degrees C), depending on the basal plasma NE levels. Compared with normotensive Wistar Kyoto rats (WKY), spontaneously hypertensive rats (SHR) had similar basal plasma E and NE concentrations, similar rates of 3H-NE disappearance, but more rapid increases to higher values of plasma NE during cold exposure. It is concluded that the basal rate of peripheral catecholamine release does not seem to be the main determining factor for arterial blood pressure in the various rat strains and that the sympathetic neuronal system of SHR is more responsive to cold exposure than that of WKY rats.

Animals↗
PubMed1982

Met-enkephalin immunoreactivity in blood platelets.

Picogram amounts (50-150 pg/mg protein) of immunoreactive met-enkephalin material (met-enkephalin IR) were detected by radioimmunoassay in human, rat and rabbit platelets. Characterization of this material by thin-layer chromatography, gel filtration chromatography and high-pressure liquid chromatography indicated that it behaves identically with synthetic met-enkephalin. No high molecular weight met-enkephalin IR could be detected in the platelet extracts, even after trypsin hydrolysis, using two antisera which are able to recognize some of the putative met-enkephalin precursors present in the adrenal gland or striatum. In vitro, thrombin released platelet-met-enkephalin IR concomitantly with 5-hydroxytryptamine (5-HT), suggesting a common subcellular localization, i.e. the 5-HT storing organelles, for met-enkephalin IR and the amine. In vivo, platelet met-enkephalin IR in the Sprague-Dawley rat was affected neither by adrenalectomy nor by hypophysectomy. Thirteen-and 18-week-old spontaneous hypertensive rats (SHR) had lower platelet concentrations of met-enkephalin IR than age matched normotensive Wistar-Kyoto rats.

Adrenal Glands↗
PubMed1982

Plasma adrenaline and noradrenaline concentrations in diabetic patients with and without autonomic neuropathy at rest and during sympathetic stimulation.

Plasma concentrations of adrenaline and noradrenaline were measured radio-enzymatically in nine patients with diabetic autonomic neuropathy, seven diabetic patients without autonomic neuropathy and nine normal subjects, in the recumbent position and after standing. Furthermore, in six patients with autonomic neuropathy and in the normal subjects, plasma noradrenaline and adrenaline concentrations were determined during and after cyclo-ergometer exercise. No differences in plasma adrenaline concentrations were found at any time in the study. Basal plasma noradrenaline levels were significantly lower in diabetic patients with autonomic neuropathy than in the non-neuropathic diabetics or healthy control subjects. After standing, plasma noradrenaline rose to significantly higher levels in both control and diabetic subjects without neuropathy than in the patients with autonomic neuropathy. During exercise (up to 100 W load), plasma noradrenaline rose to similar levels in healthy controls and in patients with diabetic neuropathy. These data indicate that in diabetic autonomic neuropathy there is reduced peripheral neurosympathetic tone at rest but a normal response to moderate exercise. Blunted neurosympathetic responses to standing seem to be a consistent feature of diabetic autonomic neuropathy, particularly in those patients with severe postural hypotension.

Adult↗
PubMed1982

Peripheral catecholamine release by alpha-latrotoxin in the rat.

Intraarterial injection of alpha-latrotoxin (alpha LTx), the major toxin of the black widow spider (Latrodectus mactans tredecimguttatus) venom, into carotid catheterized rats, induced prompt and marked rises in plasma adrenaline and noradrenaline concentrations, indicating that the toxin stimulates catecholamine release from both the adrenal medulla and sympathetic nerve terminals. Pretreatment with the ganglionic blocker chlorisondamine greatly reduced the plasma adrenaline response to alpha LTx but had almost no effect on the noradrenaline response, indicating that alpha LTx-stimulation of sympathetic nerve terminals is direct, whereas catecholamine release from the adrenal medulla is probably mediated by preganglionic release of acetylcholine. In vitro, alpha LTx induced a dose-dependent release of 3H-noradrenaline from rat irides preincubated with this radioactive amine and this effect was not changed by chlorisondamine plus atropine. By contrast, the toxin had no effect on 3H-noradrenaline release from suspensions of cultured rat chromaffin cells. Specific, high affinity binding of 125I-alpha LTx in iris and adrenal medulla homogenates was found to be exceedingly low, suggesting that it might be restricted to nerve terminals. No 125I-alpha LTx binding was seen nor could any effect of the toxin on 14C-5-hydroxytryptamine release be found in rat blood platelet preparations. alpha LTx binding and its amine releasing effect seem, therefore, to be specific for neurons and absent from other cells, even those, like adrenomedullary cells and blood platelets, which share with neurons their origin and/or other important characteristics.

Adrenal Medulla↗
PubMed1982

Effects of oral chlordemethyldiazepam on plasma adrenaline and noradrenaline and cardiovascular reactivity in preoperative patients.

In 11 preoperative women, plasma adrenaline (A) concentrations were lower after oral administration of an antianxiety dose (19.25 micrograms/kg) of chlordemethyldiazepam (Cl-DMDZ) than the predrug values, or those in 12 patients given placebo. No significant differences in supine plasma noradrenaline (NA), blood pressure (BP) and heart rate values were observed. Digital plethysmography showed finger vasoconstriction after placebo and vasodilatation after Cl-DMDZ. A mental arithmetic test caused equivalent rises in plasma A in both groups. Standing caused plasma NA to rise to similar levels in both groups of patients, but the BP decrease was less and there was a markedly lower incidence of orthostatic hypotension in the Cl-DMDZ treated group. It is concluded that the effect of Cl-DMDZ on the release of catecholamines from the peripheral sympathetic system consists essentially of decreasing basal adrenomedullary activity. CL-DMDZ appears to prevent the orthostatic hypotension which occurs when neurosympathetic reflex activation is normal.

Abortion, Induced↗
PubMed1982

[Effect of pretreatment with atenolol and propranolol on sympatho-adrenal and cardiovascular responses to acute insulin-induced hypoglycaemia in the hypertensive patient].

Plasma catecholamines and cardiovascular responses to acute insulin i.v. injection (0.12 U.I. per Kg of body weight) have been studied in eight patients with mild essential hypertension. The hypoglycaemia test was carried out before and after a week of atenolol treatment. In six patients the test was also repeated after propranolol treatment. Following insulin injection, blood sugar fell abruptly with a nadir at 30 m, diastolic blood pressure decreased, and systolic blood pressure and heart rate rose significantly. Atenolol treatment abolished almost completely these hemodynamic changes. By contrast, propranolol caused an increase in both systolic and diastolic blood pressures, leaving the heart rate unmodified. During hypoglycaemia, plasma adrenaline rose sharply in coincidence with the glycaemic nadir and declined thereafter during the glycaemic recovery. Plasma noradrenaline rose less markedly than adrenaline, but the increments were significant after 30 and 60 m. Neither atenolol, nor propranolol affected significantly these changes in plasma catecholamine concentration. These data indicate that beta-blockers do not alter the hypoglycaemia-induced adrenomedullary release of catecholamines. We conclude therefore that beta-blockers modify the pattern of the hemodynamic response to acute hypoglycaemia by interfering with the peripheral effects of circulating catecholamines in a way which depends on the degree of beta-1 selectivity of the drug used.

Adult↗
PubMed1981

Plasma catecholamines in rats exposed to cold: effects of ganglionic and adrenoreceptor blockade.

Exposure to cold (4 degrees C) of catheterized rats acclimated to 20 degrees C resulted in a progressive increase in plasma noradrenaline (NA) concentrations which reached values consistently more than twice the basal ones (20 degrees C) by about 30 min. No further increase in plasma NA levels were detected when the cold exposure was continued for 24 h. Plasma adrenaline (A) and dopamine levels did not change at any time studied. Adrenalectomized rats exposed to cold exhibited percent rises in plasma NA similar to those in intact rats. An increase in plasma A levels concomitant with that of NA was observed following exposure to cold of rats in which either basal catecholamine release was impaired by chlorisondamine or the vasoconstrictor response was impeded by phentolamine. Propranolol did not modify the acute neurosympathetic response to cold. Exposure to cold (4 degrees C) for short periods of time combined with the measurement of plasma catecholamines is proposed as a useful and reproducible method for studying a pure neurosympathetic response in the rat.

Adrenalectomy↗
PubMed1981

Blood sampling by chronic cannulation technique for reliable measurements of catecholamines and other hormones in plasma of conscious rats.

An optimalized technique for chronic venous and arterial cannulation of rodents that permits repeated blood collections in unstressed, freely moving animals is presented. The indwelling catheter can also be used for chronic and/or acute drug administration in rats or other small laboratory animals, as well as for the recording of blood pressure and heart rate. The attachment device of minimal size is easily fixed on the head of the animals, allowing the additional implantation of a chronic cannula for intracerebral injections. No residual effects on the resting levels of plasma catecholamines (CA) were present 24-hr after surgery and anesthesia for implanting the cannula. No variations of plasma CA concentrations were observed at the different times of day examined or as a consequence of withdrawal of subsequent blood samples. Training the animals to be handled prevented the increase in plasma prolactin levels produced by decapitation; training had no influence on the decapitation-induced rises in plasma CA concentrations.

Animals↗
PubMed1981

Plasma concentrations of catecholamines in two strains of spontaneously hypertensive rats at different ages.

1. Blood pressure was measured and plasma levels of noradrenaline and adrenaline were determined radioenzymatically under basal conditions and after 10% blood volume reduction in blood drawn through catheters previously implanted in young and adult rats of two different genetically hypertensive strains: the Kyoto strain (SHR) and the Milan strain (MHS), and in their respective controls: Wistar--Kyoto strain (WKY) and Milan normotensive strain (MNS). 2. Under basal conditions no differences were observed between plasma noradrenaline and adrenaline levels in SHR and MHS rats and in the controls, at any age. Haemorrhage produced a greater fall in the blood pressure (P less than 0.01) of young and adult hypertensive strains (SHR-MHS) than in WKY and MNS rats, and a greater rise in plasma adrenaline (P less than 0.01). 3. These results suggest that: (a) there may be differences in involvement of the sympathetic nervous system in the pathogenesis of hypertension in SHR and MHS rats but not such as to cause differences in plasma catecholamine levels in either young or adult rats; (b) haemorrhage activates the sympatho--adrenal systems more in SHR and MHS rats, than in controls, and the greater percentage fall in blood pressure is probably due to a difference in reflex venoconstriction.

Aging↗
PubMed1981

Plasma catecholamine response to postural stimulation in normotensive and dialysis hypotension-prone uremic patients.

The neurosympathetic responsiveness of two groups of uremics, each group treated for the same mean time by dialysis, categorized as normotensive, mean age 28.3 +/- (SE) 3 years, or dialysis hypotension-prone, mean age 49.6 +/- 5 years, was studied by determining plasma norepinephrine and epinephrine before and after postural activation of the sympathetic reflex arc. The study was performed on an interdialysis day and repeated 20 min before and after a regular dialysis on the following day. Standing caused norepinephrine to rise significantly in both the normotensive and the hypotension-prone groups and to a similar extent as in a control nonuremic group. Blood pressure did not change and the heart rate increased significantly. Plasma norepinephrine before dialysis 24 h later behaved in the same way, but both blood pressure and heart rate were unchanged. After dialysis, in spite of the usual increase in norepinephrine after standing, patients in the hypotension-prone group became hypotensive. These results suggest that there is a normal sympathetic responsiveness in uremics whatever their propensity for intradialysis hypotension. Moreover, dialysis does not seem to have an acute effect on the neurosympathetic response to a hypotensive stimulus. Dialysis-dependent hypotension, which appears to be more frequent in older subjects, probably reflects an impairment of the vasoconstrictor response of the vascular wall acutely induced by dialysis itself.

Adolescent↗
PubMed1981

Intravenous labetalol in severe hypertension. Effects on blood pressure, plasma renin activity and catecholamines.

2-Hydroxy-(1-hydroxy-[(1-methyl-3-phenylpropyl)amino]-2-ethyl)-5-benzamide (labetalol), a new alpha- and beta-adrenergic blocking agent, was employed in 21 patients with severe hypertension by slow (6 patients) and rapid (15 patients) i.v. infusion. A marked and significant fall of blood pressure was observed in both groups, though more gradual in patients treated by slow infusion. A rapid blood pressure fall with cardiac output decrease was observed by passing from supine to standing position in the first hours after infusion. Therefore, it is advisable to keep a supine position for a few hours. Plasma renin activity decreased after labetalol infusion, but basal plasma renin levels were not related to hypotensive effect of labetalol. In slow infusion patients, plasma noradrenaline levels increased and no changes of plasma adrenaline levels were observed during infusion. The most likely explanation of these variations is an increase of sympathetic activity secondary to hypotension, caused by labetalol, whereas a technical interference seems to be excluded. The simultaneous blockade of alpha- and beta-receptors can inhibit, in this case, the pressor effects of the sympathetic reflex.

Adult↗
PubMed1980

Plasma catecholamines and plasma renin activity at birth and during the first days of life.

1. Plasma noradrenaline and adrenaline concentrations and plasma renin activity were measured in 21 mothers at delivery and in their babies at birth (umbilical cord blood) and on days 1 and 5 of extrauterine life. 2. At birth plasma renin activity was significantly higher in the newborn than in mothers. Plasma renin activity increased further, but not significantly, on day 1 of life and significantly decreased on day 5. On day 5, 10 min head-up tilting caused no change in plasma renin activity. 3. Plasma noradrenaline in the newborn was higher than in mothers at birth and significantly decreased thereafter. Plasma adrenaline levels at birth were similar in the newborn and their mothers and significantly lower in the newborn in subsequent days. Tilting caused no increase in either plasma adrenaline or noradrenaline levels. 4. No correlation was found between plasma noradrenaline and adrenaline levels and plasma renin activity, or between noradrenaline, adrenaline or plasma renin activity and blood pressure.

Blood Pressure↗