Showing papers by "Giuseppe Mancia published in 1986"

Reflex control of the human cardiovascular system

Abstract: The surge of knowledge about the autonomic regulation of the human cardiovascular system which commenced in the 1940s was a consequence of many events. These included the information gained from animal studies of the various reflexogenic zones which modulate the circulation, the demonstration of the feasibility of cardiac catheterization in man; the urgent need in the Second World War for information on the effects of gravitational forces on the human cardiovascular system which were encountered in military aircraft; the development of instrumentation and techniques applicable to human studies; and the growing number of clinician-scientists able to divise and conduct appropriate studies and of informed volunteers willing to act as subjects for the experiments. To these should be added the demonstration in 1948, in the splenic nerves of the ox, that norepinephrine was the sympathetic neurotransmitter (von Euler 1948) and in the same year the development of the concept of two types of adrenoceptors, alpha and beta (Ahlquist 1948).

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

Abstract: Summary: 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 baroflex 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. These findings show that in contrast with many beta blockers, celiprolol causes a forearm vasodilatation in hypertensive humans. The baroreceptor and cardiopulmonary receptor control of the cardiovascular system is not impaired and may even be enhanced by the drug. This ensures that, regardless of its mechanisms of action, celiprolol does not adversely affect circulatory homeostasis.

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

Abstract: 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

Neural Mechanism in Human Cardiovascular Regulation

Abstract: A large number of animal studies have shown that neural factors exert a major control over the cardiovascular system (Kirchheim 1976; Korner 1979) and that derangement of this control may play an important role in the pathophysiology of cardiovascular diseases, such as essential hypertension, angina pectoris, myocardial infarction and sudden death (Folkow 1982). However evaluation of neural factors involved in cardiovascular regulation in human beings is difficult, both because of their complexity and because of the paucity and the limitations of the techniques available for this purpose (Mancia and Mark 1983).