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Biomedical subjects

A Zanchetti

Publications and source records attributed to A Zanchetti.

At least 325 records · Page 18Linked to original sources
PubMed1987

Afferent pathways of neural reno-renal reflexes controlling sodium and water excretion in the cat.

We have studied the role of afferent renal nerve fibres in anaesthetized cats in mediating the decrease in sodium and water excretion from the contralateral kidney caused by unilateral renal denervation. Transient denervation of one kidney obtained by cooling of the left renal nerves increases contralateral efferent renal nerve activity and decreased sodium and water excretion from the opposite kidney. The results observed in animals with intact neural pathways were compared with those obtained after the left kidney had been selectively deafferentated by cutting the dorsal roots from T9 to L4. Bilateral section of dorsal roots did not affect the increase in sodium and water excretion from the transiently denervated left kidney, but entirely abolished the decrease in sodium and water excretion from the contralateral kidney. Neither the left nor the right dorsal root section alone, affected the response of the contralateral right kidney. Our data demonstrate that afferent renal nerve fibres project bilaterally to the spinal cord and form the afferent branch of the reno-renal reflex by which one kidney can control the function of the opposite one.

Afferent Pathways↗
PubMed1986

Comparison of the antihypertensive effect of urapidil and metoprolol in hypertension.

The hypertensive effect of urapidil, a new antihypertensive agent that acts via central and peripheral alpha-adrenoceptors, has been compared with that of metoprolol in 40 patients with mild essential hypertension. Blood pressure was significantly reduced by both drugs, while the heart rate was reduced only after metoprolol. The increases in systolic blood pressure and heart rate caused by three progressive work loads of bicycle exercise were not affected during urapidil, whereas both were reduced by metoprolol. A slight reduction in forced expiratory volume was observed in some patients during treatment with the beta-blocker. There was no case of orthostatic hypotension during urapidil administration, despite its alpha1-blocking action. Side-effects were rare and negligible with both drugs.

Adult↗
PubMed1986

Effects of reversible renal denervation on haemodynamic and excretory functions of the ipsilateral and contralateral kidney in the cat.

In anaesthetized cats reversible denervation of one kidney was performed by cooling of the left renal nerves to 3 degrees C for 16 min. The response of the left (ipsilateral) kidney was compared with the response of the right (contralateral) kidney twice in the same animal: (1) when the right kidney was still innervated, and (2) after it had been surgically denervated. Left renal nerve cooling did not cause any changes in arterial pressure. In the left kidney, blood flow, vascular conductance, sodium and water excretions increased, and renin release decreased. Simultaneously in the contralateral kidney, no haemodynamic changes were observed, glomerular filtration was only transiently decreased, whereas sodium and water excretion significantly decreased and renin release increased. When left renal nerve cooling was repeated after surgical denervation of the right kidney, similar changes were observed in the left (ipsilateral) kidney, whereas all contralateral effects were abolished. These experiments suggest that tonically active afferent fibres from one kidney exert a reflex inhibitory action on sympathetic activity directed to the contralateral kidney controlling tubular sodium reabsorption and renin release.

Animals↗
PubMed1986

The development of new antihypertensive drugs with specific properties for the treatment of established hypertension.

Despite the significant blood pressure reduction achieved in clinical studies of antihypertensive therapy, including the Medical Research Council studies, there has not been a significant reduction of coronary events. Different hypotheses have been proposed to explain the lack of cardioprotection seen in different trials, such as alterations of serum potassium and/or plasma lipids. Recent data indicate that patients with left ventricular hypertrophy at the start of pharmacologic treatment have a worse prognosis than patients with no electrocardiographic abnormalities. It is not known, however, whether the regression or persistence of left ventricular hypertrophy during antihypertensive treatment can influence the incidence of coronary events. According to present knowledge, indoramin, an alpha-adrenoceptor blocking drug, does not affect serum electrolyte and plasma lipid levels, which are among the characteristics to be evaluated in clinical trials designed to evaluate the possibility of better cardioprotection.

Antihypertensive Agents↗
PubMed1986

Effects of celiprolol on reflex control of the cardiovascular system in essential hypertension.

We have previously shown that baroreceptor control of the cardiovascular system and the cardiopulmonary receptor control of peripheral circulation are preserved or only moderately reduced during antihypertensive treatment with acebutolol or nadolol, which indicates that treatment with beta blockers with or without intrinsic sympathomimetic activity does not impair fundamental neural mechanisms involved in circulatory homeostasis. In the present study we have investigated the reflex control of circulation before and during antihypertensive treatment with celiprolol, which, in addition to its beta-blocking action, has vasodilator properties that may stem from interference with neural cardiovascular control. In six essential hypertensive subjects we measured blood pressure (intraarterial catheter), heart rate (ECG recording), central venous pressure (right atrial catheter), and forearm blood flow and resistance (plethysmography) before and during alterations in the activity of the arterial baroreceptors obtained by means of lower body suction and passive leg raising. The study was performed before and after 5-7 days of oral administration of celiprolol at 200-400 mg once a day. Compared to the values obtained in the control, condition celiprolol caused a reduction in blood pressure, a slight change in heart rate, and an increase in forearm blood flow, which indicated the occurrence of a clear-cut forearm vasodilatation. The heart rate responses to arterial baroreceptor manipulation were unchanged by celiprolol which reset the carotid baroreflex so that its tonic restraint on blood pressure increased despite the hypotension induced by the drug. The inhibitory restraint tonically exerted by the cardiopulmonary receptors on peripheral circulation was also increased by celiprolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Acebutolol↗
PubMed1986

Control of circulation by arterial baroreceptors and cardiopulmonary receptors in hypertension.

This article reviews observations made on reflex control of circulation in essential hypertension and in a few models of experimental hypertension. It is emphasized that a wide consensus exists on the fact that baroreceptor control of heart rate is impaired in essential hypertension and that this occurs not only in severe but also in mild and borderline hypertensive conditions. On the other hand, baroreceptor control of blood pressure is much less affected by chronic elevations in arterial blood pressure due to central or peripheral factors that differentially affect cardiac and vascular responses to the vagus and the sympathetic drive, respectively. Cardiopulmonary receptor control of peripheral circulation and renin release is also little affected by hypertension, and the suggestion has been made that its sensitivity may even be enhanced in early hypertensive stages and then undergoes a subsequent reduction as cardiac hypertrophy develops. Finally, the possible consequences of preservation of reflex control of circulation in hypertension are discussed. It is speculated that this phenomenon may be in part responsible for the similar percentage of blood pressure oscillations that can be observed in normotensive and borderline, moderate, and severe hypertensive subjects.

Animals↗
PubMed1986

Antihypertensive therapy and cardiovascular complications.

Hypertension is a quantitative derangement of a physiological parameter rather than a disease and acceptance of this fact has greatly influenced the treatment of hypertension. Experience gathered over many years can be critically analysed to gain further information about the treatment of hypertension and the effect of different treatments on the complications of hypertension. The extent to which hypertension is a causative risk factor for coronary heart disease is still disputed, a lowering of blood pressure having not yet been conclusively shown to be invariably associated with a reduction in the incidence of coronary heart disease. On the other hand, a causative relationship with cerebro-vascular disease has been convincingly shown. This raises the possibility that, at least for coronary heart disease, the way in which blood pressure is lowered may be important. Many treatments for hypertension affect other parameters, e.g., electrolytes and plasma lipids, and it may be that a positive effect on blood pressure may be offset by a negative effect on another parameter. Evidence that this is indeed the case with diuretics has emerged from a number of large-scale trials. The cardio-protective effect of beta blockers has also recently been extensively examined, although no clear conclusions have yet been reached. Primary prevention and secondary prevention are not the same, and positive results in one do not necessarily mean that the same drug will be effective in the other. A number of trials have been carried out to gain more information about the value of beta blockers, but it is unlikely that conclusive evidence will emerge due to the small difference in the therapies compared and the relatively short duration of the trials.

Antihypertensive Agents↗
PubMed1986

Antihypertensive and renal effects of tertatolol, a new beta-blocking agent, in hypertensive patients.

Tertatolol, a new nonselective beta-adrenoceptor blocker, was administered to 11 hypertensive patients in a short-term study. Systolic and diastolic blood pressure and heart rate were significantly decreased when compared to the placebo period: in spite of that glomerular filtration rate and renal plasma flow were unchanged. The administration of metoclopramide (a dopaminergic receptor antagonist) caused a significant reduction of renal plasma flow and a significant rise of renal vascular resistances during placebo, but no change during tertatolol therapy. A possible interference of tertatolol on dopaminergic receptors is discussed as the mechanism responsible for the unmodified renal plasma flow despite the significant blood pressure lowering with tertatolol.

Adrenergic beta-Antagonists↗
PubMed1986

Arterial baroreflexes and blood pressure and heart rate variabilities in humans.

The factors responsible for 24-hour blood pressure and heart rate variabilities have never been clarified; however, studies performed in unanesthetized animals have shown an increase in blood pressure variability after sinoaortic denervation, and a negative relationship has been reported occasionally between blood pressure variability and baroreflex control of heart rate in humans. We have systematically investigated this issue in 82 ambulant hypertensive subjects using 24-hour intraarterial blood pressure recording (Oxford method) in which blood pressure and heart rate variabilities were measured by calculating the standard deviations of the values obtained throughout the 24 hours or during separate daytime and nighttime periods. Baroreflex sensitivity was assessed by the bradycardic or tachycardic responses to intravenous injections of phenylephrine or nitroglycerin and by the blood pressure response to changes in carotid transmural pressure obtained with a neck chamber. The sensitivity of the baroreceptor-heart rate reflex as assessed by the vasoactive drug technique showed a negative relationship with 24-hour blood pressure variability as well as with daytime and nighttime blood pressure variabilities measured separately (r = -0.28 to -0.50, p less than 0.05). These variabilities also correlated negatively with the sensitivity of the baroreceptor-blood pressure reflex as assessed by the neck chamber technique. By contrast, baroreflex sensitivity showed a positive correlation with heart rate variabilities (r = 0.32 to 0.47, p less than 0.05). The relationship between baroreflex sensitivity and blood pressure and heart rate variabilities was confirmed when the data were analyzed by multiple regression to adjust for blood pressure and age differences among the 82 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Volhard lecture: sympatho-renal interactions and blood pressure control.

Among the various mechanisms of cardiovascular control that might be involved in the pathogenesis of arterial hypertension, either as causative or as maintaining factors, attention has long ben devoted to the sympathetic nervous system and to the kidney. There is increasing evidence that the sympathetic nervous system and the kidney can interact in various ways, the kidney being both a target of sympathetic activity and a source of influences on the sympathetic system. The positive-feedback nature of most of these interactions suggests that sympatho-renal interactions participate in the pathogenesis of arterial hypertension, both when the initiating factor is neural and when it is renal.

Animals↗