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Biomedical subjects

A Zanchetti

Publications and source records attributed to A Zanchetti.

At least 415 records · Page 23Linked to original sources
PubMed1979

Plasma catecholamines and blood pressure responses to the carotid baroreceptor reflex in essential hypertension.

1. Slight decreases and increases in carotid baroreceptor activity were induced in subjects with essential hypertension by slight alterations in carotid transmural pressure (variable pressure neck-chamber technique) in order to obtain limited increases and reductions in sympathetic adrenergic activity. 2. When sympathetic activity was reflexly increased there was a rise in arterial pressure but no significant increase in plasma catecholamines. Likewise when sympathetic activity was reflexly reduced there was a fall in arterial pressure but no significant reduction in plasma catecholamines. 3. Plasma noradrenaline and adrenaline significantly and markedly increased in the same subjects when sympathetic activity was increased by activation of both arterial and low pressure baroreceptor reflexes with tilting. 4. It is suggested that measurements of catecholamines in systemic plasma may reveal marked degrees of sympathetic activation but may not be a sensitive index of more moderate changes in sympathetic tone.

Adult↗
PubMed1979

Vagal and sinoaortic reflexes in postural control of circulation and renin release.

Anesthetized cats were subjected to two 10-min trials of head-up tilting spaced 60 min apart. Bilateral cervical vagotomy, performed after the first tilting episode, did not affect the hemodynamic response to the change in posture, but significantyly and markedly reduced the increase in renin release from the innervated kidney. After sinoaortic denervation a marked and sustained arterial hypotension occurred during tilting, and the postural increase in renin release, though still limited to the innervated kidney, was even greater. When pressure homeostasis to tilting was disturbed, the renin release response was seen to be independent of the vagi, as it occurred after combined vagotomy and sinoaortic denervation. Maintenance of arterial pressure during tilting is mainly due to sinoaortic reflexes, whereas vagal reflexes are mostly responsible for the postural increase in renin release. The vagally independent release of renin observed when the cardiovascular response to tilting is impaired, is probably due to a direct action of arterial hypotension on intrarenal receptors, an action occurring only in innervated kidneys.

Animals↗
PubMed1979

Cardiovascular changes during spontaneous micturition in conscious cats.

The hemodynamic changes occurring during spontaneous micturition were recorded in conscious cats. Arterial blood pressure was continuously measured by chronically implanted arterial catheter, heart rate (HR) by a cardiotachometer, and cardiac output (CO), superior mesenteric (MF), renal (RF), and external iliac blood flows (IF) by chronically implanted electromagnetic flow probes. Spontaneous micturition was accompanied by little change in mean arterial pressure (-9.7 +/- 0.7%), but by a marked decrease in HR (-49.0 +/- 1.2%) and CO (-28.6 +/- 2.5%), and therefore by a marked decrease in total peripheral conductance (-21.0 +/- 3.5%). Visceral and hindlimb blood flows were markedly reduced during micturition (MF, -34.7 +/- 2.1%; RF, -22.6 +/- 1.5%; and IF, -48.7 +/- 1.5%, respectively) due to a marked reduction in regional conductances in both these areas. The vasomotor changes in the regional circulations were prevented by local sympathectomy. Thus spontaneous micturition is associated with marked changes in cardiac function and systemic circulation. Cardiac output is decreased, but diffuse nervous systemic vasoconstriction compensates for this and provides maintenance of arterial blood pressure level.

Animals↗
PubMed1978

Differences in reflex control of arterial pressure and renin release during head-up tilting in the cat.

1. Anaesthetized cats were subjected to two 10 min trials of head-up tilting spaced 30 min. Arterial pressure, heart rate, blood flow to an innervated kidney and to the contralateral denervated one, and renin release from both kidneys were measured. 2. The same haemodynamic changes and comparable increases in renin release from innervated kidneys occurred during both episodes of tilting when cats were subjected to sham cervical vagotomy between the two tilting trials. 3. Bilateral cervical vagotomy, performed after the first episode of head-up tilting, did not affect the haemodynamic response to the change in posture, but significantly and markedly reduced the increase in renin release from the innervated kidney. 4. After sino-aortic denervation a marked and sustained arterial hypotension occurred during tilting, and the postural increase in renin release from the innervated kidney was even greater. 5. In no condition, even during the marked fall in blood pressure in sino-aortic denervated cats, did head-up tilting increase renin release from the denervated kidney. 6. It is concluded that maintenance of arterial pressure during tilting is mainly due to sino-aortic reflexes, whereas vagal reflexes are mostly responsible for the postural increase in renin release.

Afferent Pathways↗
PubMed1978

Relationship between the hypotensive and renin-stimulating actions of diuretic therapy in hypertensive patients.

1. The pressor role of renin stimulated by chronic diuretic therapy has been assessed in 31 patients with essential hypertension by infusing the angiotensin II antagonist, saralasin, immediately before and at the end of 2 weeks' treatment with the diuretic, chlorthalidone. 2. Under diuretic therapy the change in blood pressure caused by saralasin was found to be correlated to plasma renin activity values, in such a way that small pressor responses were again observed in patients whose renin was mildly stimulated by the diuretic, whereas a marked depressor response occurred in patients whose renin was markedly increased. 3. On the other hand, the hypotensive effect of chlorthalidone was correlated to values of plasma renin activity under diuretic therapy in an opposite direction: indeed little or no decrease and sometimes an increase in blood pressure were observed in patients with marked renin activation by diuretic therapy. 4. It is concluded that stimulation of renin release by chronic diuretic therapy can be considered a factor limiting the hypotensive activity of diuretic drugs.

Adult↗
PubMed1978

Control of regional circulations by the sino-aortic reflexes during desynchronised sleep in the cat.

In the intact cat desynchronised sleep induces arterial hypotension and mesenteric vasodilatation, whereas in limb muscles vasoconstriction occurs because of the concurrent action of a spinal vasoconstriction reflex. After sino-aortic denervation arterial hypotension is exaggerated and mesenteric vasodilatation is greater, while the muscular bed of the limbs also becomes vasodilated rather than constricted. It is concluded that during desynchronised sleep the sino-aortic afferents act to check a central influence inhibiting vasoconstrictor tone both in the viscera and muscles: thus an excessive fall in blood pressure is prevented by avoiding a too large visceral vasodilatation and by unmasking the vasoconstrictor action of the spinal reflex in the limbs.

Animals↗
PubMed1978

Baroreceptor reflexes in human hypertension.

We studied the control of arterial pressure by the carotid sinus baroreceptors in 35 hypertensive humans, using a variable pressure neck chamber to alter carotid sinus transmural pressure in a graded fashion. The results were compared with those obtained from 11 normotensives. As in normotensives, reduction in carotid transmural pressure caused a linearly related pressor response and vice versa. However, whereas in normotensives the pressure response was greater than the depressor, the reverse was the case in hypertensives. Furthermore, the pressor response decreased and the depressor response increased progressively with an increase in severity of the hypertension. Thus while in normotensives the carotid baroreflex is more effective in protecting against hypotension, in hypertensives the antihypertensive function of the reflex is favored. Similar differences between hypertensives and normotensives were found with respect to the carotid baroreceptor control of heart rate. In eight hypertensives, reflex changes in heart rate also were studied by injection of phenylephrine and trinitroglycerine to vary not only carotid baroreceptor activity, but also activity of extracarotid baroreceptors. The results were compared with results of similar studies on eight normotensives. These comparisons suggest that, whereas the carotid baroreceptor reflex remains active in hypertension, reflexes stemming from extracarotid baroreceptor areas are much diminished.

Adult↗
PubMed1978

Considerations on physiopathological approaches to the treatment of hypertension.

1. Two main physiopathological approaches to the treatment of hypertension are discussed, the first based on renin profiling and the second on haemodynamic measurements. 2. Reduction in plasma renin activity does not appear to be a clinically important mechanism in the hypotensive effect of beta-adrenergic blockers and of alpha-methyldopa. In particular, alpha-methyldopa has been found equally effective as a hypotensive agent both in normal renin and in low renin hypertensive patients. 3. Diuretics are certainly possessed of a renin-stimulating action, but in most patients this action does not obscure the hypotensive effect of these drugs. 4. Responders and non-responders to the hypotensive activity of beta-adrenergic blockers do not differ among them in their control haemodynamics.

Adrenergic beta-Antagonists↗
PubMed1977

Plasma renin activity in primary and secondary depression.

Plasma renin activity (PRA), both in supine and standing position, was investigated in primary and secondary depressed patients. After orthostatic stimulation (standing position) primary depressed patients showed PRA values significantly lower than did those with secondary depression. The authors stress the importance of the peripheral sympathetic system in the control of renin release and discuss the data obtained in the light of some evidence in the literature indicating a possible impairment of transmitter turnover in central and peripheral noradrenergic synapses in the pathogenesis of primary depression.

Adjustment Disorders↗