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Biomedical subjects

A Zanchetti

Publications and source records attributed to A Zanchetti.

At least 379 records · Page 21Linked to original sources
PubMed1983

Reversible alteration of myocardial function in gestational diabetes.

Left ventricular function was evaluated in 24 women who developed impaired glucose tolerance only during their pregnancy, i.e. patients with gestational diabetes. The results were compared with those of 25 normal pregnant women and with those of 17 pregnant women with clinical diabetes. The method of systolic time intervals was applied. At the third trimester of pregnancy, both the women with overt diabetes and those with gestational diabetes, when compared with normal pregnant subjects, had a more prolonged pre-ejection period (PEP) and a shorter left ventricular ejection time (LVET) and, consequently, a higher PEP/LVET ratio. Five weeks after delivery, abnormalities of systolic time intervals persisted in patients with clinical diabetes, but there were no differences at this time between patients with gestational diabetes and those in the control group. It is concluded that when a cardiac load is superimposed on patients who develop diabetes only under conditions of stress, as in pregnancy (gestational diabetes), abnormalities of myocardial function appear, which revert to normal when the stressful event is removed.

Adolescent↗
PubMed1983

Alterations of systolic time intervals in the assessment of myocardial function during hypertensive pregnancy.

The alterations in the systolic time intervals caused by hypertension during pregnancy have been investigated. A group of 20 women who developed hypertension only during pregnancy (HP), and a group of 16 women who began pregnancy with established hypertension (EHP) were matched with 25 normal pregnant women (N). the study was performed (1) during the third trimester, (2) five days after delivery and (3) five weeks after delivery, both in supine and in lateral postures. In the third trimester the two hypertensive groups, when compared with the normal group, were characterized by a shorter left ventricular ejection time (LVETi: 407 +/- 3 ms for the normal group v. 390 +/- 2 ms for the HPO group, P less than 0.001; v. 398 +/- 2 ms for the EHP group, P less than 0.02), and a longer pre-ejection period (PEPi: 138 +/- 2 ms for the normal group v. 154 +/- 2 ms for the HP group P less than 0.001; v. 145 +/- 1 ms for the EHP group, P less than 0.05). When the two hypertensive groups were compared with each other the HP group showed a shortened LVET and a prolonged PEP (P less than 0.01), and also a slower heart rate (HP 74 +/- 3 b min-1. EHP 83 +/- 3 b min-1 P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Do renal afferent fibres modulate the function of the contralateral kidney?

Denervation of one kidney has been shown to induce a prompt decrease in sodium and water excretion from the contralateral kidney. The present study was designed to clarify whether this response is due to suppression of a tonic inhibitory renorenal reflex. Experiments were performed in anaesthetized cats in which the renal nerves of the left kidney were transiently blocked by cooling and the effects of this blockade on either kidney were studied in three different groups of animals. The decrease in sodium and water excretion from the contralateral (right) kidney observed in the sham-operated group (intact dorsal roots) was still present, and substantially unchanged, in the second group of animals in which the ipsilateral (left) dorsal roots from T9 to L4 were cut. In the third group of cats, bilateral dorsal root section entirely abolished the response of the contralateral kidney to renal nerve cooling. These experiments demonstrate that the contralateral decrease in sodium and water excretion is due to the block of afferent renal nerve fibres which project bilaterally to the spinal cord.

Afferent Pathways↗
PubMed1982

Modification of arterial baroreflexes by captopril in essential hypertension.

Captopril lowers blood pressure without increasing heart rate and plasma norepinephrine, which suggests that this drug may potentiate arterial baroreflexes. In eight subjects with untreated essential hypertension, blood pressure was monitored intraarterially and the effects of baroreceptor stimulation or deactivation were assessed by measuring (1) the slopes of the relations between increase or reduction in systolic pressure (intravenous phenylephrine or nitroglycerin) and the resulting lengthening or shortening in R-R interval, and (2) the increase or decrease in mean arterial pressure induced by increasing and decreasing carotid transmural pressure (neck chamber). The measurements were made before and after a hypotensive oral dose of captopril (50 mg). Before captopril, the slopes of the R-R interval changes with increase and reduction in systolic pressure were 8 and 4 ms/mm Hg, respectively. The slopes of the mean arterial pressure changes with increase and reduction in carotid transmural pressure were 0.51 and 0.40 mm Hg, respectively. After captopril, the responses to baroreceptor stimulation were unaltered but those to baroreceptor deactivation were augmented. The pressor and heart rate responses to hand-grip and cold exposure were unchanged by captopril. Administration of captopril is accompanied by a baroreflex potentiation which involves the lower portion of the stimulus-response curve of the reflex. This phenomenon (which may originate at the afferent baroreceptor fibers or centrally) may avoid a reduction in the tonic baroreflex influence during captopril-induced hypotension, thus contributing to the hemodynamic effects of the drug.

Adult↗
PubMed1982

Acute hypotensive and renin-stimulating actions of captopril before and during treatment with a beta-blocking drug.

There is no general agreement on the relation between the hypotensive effect of captopril and the pretreatment plasma renin levels of hypertensive patients. To determine whether the hypotensive effect of captopril was directly related to plasma renin, the angiotensin-converting enzyme inhibitor was administered acutely to 10 essential hypertensive patients with normal or suppressed plasma renin activity before and after inhibition of renin secretion with propranolol. Captopril was equally effective in reducing blood pressure both when administered alone (25 mg: -29/-17; 50 mg: -37/-23 mm Hg) and after chronic treatment with propranolol (25 mg: -33/-20; 50 mg: -30/-20 mm Hg). The increase in renin induced by captopril was not decreased by propranolol therapy. The persistence of the hypotensive effect of captopril after renin suppression by propranolol suggests that this drug has some blood pressure decreasing properties independent of plasma renin.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1982

Dissociation of the effects of alpha 1-adrenergic blockade on blood pressure and renin release in patients with essential hypertension.

Prazosin, a selective antagonist of postsynaptic alpha-adrenoreceptors, was used to investigate the influence mediated by the juxtaglomerular alpha-adrenoreceptors on renin release in man. We studied, in seven patients with essential hypertension, the acute effects of 0.25 mg prazosin, given intravenously, on blood pressure and plasma renin activity, the degree of alpha-blockade induced by the drug being assessed by comparing the increments in blood pressure following a test dose of phenylephrine before and after prazosin administration. We also measured the increments in plasma renin activity in response to beta-adrenergic stimulus consisting of an isoproterenol challenge, before and during the prazosin induced alpha blockade. Prazosin infusion caused, within 20 min, a marked reduction of the pressor response to phenylephrine, a significant increment in plasma renin activity, and no change in blood pressure. The increments in renin in response to isoproterenol were significantly greater, both in absolute and percent values, after rather than before prazosin. These results indicate that the increase in renin during systemic alpha 1-adrenoreceptor blockade may be independent of the fall in blood pressure and support the view that the juxtaglomerular alpha 1-adrenoreceptors participate in the regulation of renin release with an inhibitory action, which antagonizes the stimulating influence of the beta-adrenoreceptors.

Adolescent↗
PubMed1982

Blood pressure response to labetalol in twice and three times daily administration during a 24-hour period.

1 The anti-hypertensive effect of labetalol given twice or three times daily was evaluated in ambulant subjects with essential hypertension by recording blood pressure directly for 24 h before and after 15 d of labetalol administration (daily dose 600-1800 mg). 2 Labetalol reduced 24 h systolic and diastolic blood pressures by about 20%. The reduction was evident throughout the whole 24 h period, although it was less marked during sleep. The hypotensive effect was similar when the drug was given twice or three times daily. 3 The 24 h heart rate was reduced during labetalol treatment. However, this effect was less marked than the hypotensive effect and was not present in all subjects. 4 There was a reduction in the standard deviations of blood pressure and heart rate values. However, in neither case was the coefficient of variation altered, indicating that labetalol did not have any significant effect on the shape of the 24 h blood pressure measurements.

Adult↗
PubMed1982

Antihypertensive therapy in patients above age 60 with systolic hypertension. A progress report of the European Working Party on High Blood Pressure in the Elderly (EWPHE).

1. Although systolic blood pressure elevation is responsible for increased incidence of cardiovascular accidents in old people, the preventive benefit of lowering systolic hypertension in elderly has not been confirmed. 2. A double blind study comparing the effects of a placebo and of an active regimen (hydrochlorothiazide-triamterene with or without methyldopa) in people over 60 years with isolated systolic hypertension has been undertaken by the European Working Party on High blood pressure in the Elderly (EWPHE). 3. The actively treated group shows a lowered sitting blood pressure (-15/6 mm Hg), a mild increase of serum creatine, serum uric acid and blood glucose and a mild decrease of serum potassium after two years of treatment when compared to the spontaneous changes observed in the placebo treated group. 4. The study is continuing to evaluate if the blood pressure reduction prevents or reduces the incidence of cardiovascular accidents, although some biochemical changes were provoked by the treatment.

Aged↗
PubMed1982

Time course of the changes in active and cryoactivatable renin in response to acute stimuli before and after diuretic therapy in man.

In order to elucidate whether inactive renin may represent a precursor of the active enzyme we examined the short-term effects of ambulation and of Captopril administration on active and cryoactivatable renin in patients with essential hypertension before and after 5 days of diuretic therapy. We have found that in the large majority of patients before diuretic the increments in active renin in response to these stimuli were moderate and associated with unchanged levels of cryoactivatable renin; significant decrements in cryoactivatable renin were observed only in a small group of patients in whom the increments in active renin induced by ambulation were unusually rapid and marked. Diuretic therapy caused parallel increments in baseline values of active and of cryoactivatable renin and potentiated the response of the active enzyme to ambulation and to Captopril; however, cryoactivatable renin was still unmodified during both the acute stimuli. Thus, it appears that, normally, the rise in active renin induced by ambulation and Captopril administration is associated, both before and after diuretic therapy, with unchanged levels of the inactive enzyme; however, before diuretic, abrupt increments in the demand for active renin can determine changes in opposite direction of inactive renin as if the latter were a precursor of the former.

Adolescent↗
PubMed1982

Comparison of cardiovascular, renal, and humoral effects of acute administration of two calcium channel blockers in normotensive and hypertensive subjects.

The acute effects of two calcium channel blockers, nifedipine and verapamil, were compared in eight normotensive subjects and eight patients with essential hypertension. Nifedipine 10 mg and verapamil 160 mg orally had no effect on blood pressure of normal subjects, but reduced systolic and diastolic pressures of hypertensive patients to the same extent. The blood pressure reduction caused by nifedipine was more prompt and of lesser duration than that caused by verapamil. In both normal subjects and hypertensive patients nifedipine caused a transient rise in heart rate and plasma renin activity, and plasma catecholamines showed a tendency to increase; verapamil did not affect these variables. Nifedipine induced a marked increase in urine volume and renal sodium excretion in hypertensive patients, with a much smaller change in normotensives. Verapamil did not influence water and sodium excretion in either direction. Thus, this study shows similarities and differences between the effects induced by acute oral administration of the most-used vasodilating calcium antagonists.

Blood Pressure↗