Activity of the Adrenal Medulla and its Regulation

Malméjac, J

doi:10.1152/physrev.1964.44.2.186

Cited by 62 publications

(32 citation statements)

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“…MUSCLE CIRCULATION IN HYPOXIA Adrenaline is the major adrenal medullary hormone of the rabbit (H6kfelt, 1951;Shepherd & West, 1952;Malmejac, 1964). It appears to be the main factor in restoring muscle blood flow to normal in moderate hypoxia and elevating it above resting values during severe hypoxia, since the experiments in fl-blocked and adrenalectomized animals demonstrate that the increase in x-constrictor activity is more than sufficient to overcome the local vasodilator effects of hypoxia on muscle.…”

Section: Discussionmentioning

confidence: 99%

“…It seems likely that a 713 714 J. P. CHALMERS, P. I. KORNER AND S. W. WHITE different reflex mechanism may be involved in the release of adrenaline. In severe arterial hypoxia the baroreceptor reflexes, stimulated by the small fall in blood pressure, probably contribute to the elevation of adrenaline secretion (Heymans & Neil, 1958;Malmejac, 1964).…”

Section: Discussionmentioning

confidence: 99%

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The control of the circulation in skeletal muscle during arterial hypoxia in the rabbit

Chalmers

Korner²,

White³

1966

The Journal of Physiology

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SUMMARY1. The effects of arterial hypoxia on muscle blood flow were examined in normal unanaesthetized rabbits in relation to simultaneously determined changes in cardiac output, arterial pressure and heart rate. Muscle blood flow was estimated from the difference between total limb flow (local thermodilution) and the estimated skin flow (using a calibrated heat conductivity method). The role of the arterial chemoreceptors and baroreceptors in the control of muscle blood flow was examined and the nature of the sympathetic efferent discharge analysed. followed by a return to control values paralleling the changes in cardiac output. In severe arterial hypoxia (Po2 < 30 mm Hg) the initial vasoconstriction was less marked, and during the 'steady state' there was a large vasodilatation and increase in muscle blood flow, at a time when the cardiac output was not elevated.3. The early vasoconstriction in arterial hypoxia is mediated mainly through sympathetic vasoconstrictor nerves as a result of strong arterial chemoreceptor stimulation.4. Increased secretion of adrenaline is an important factor in restoring muscle blood flow to control values during moderate arterial hypoxia, and in elevating the muscle blood flow above these values in severe hypoxia.The peripheral dilator (,8-) effects of adrenaline oppose the peripheral constrictor (a-) effects resulting from increased activation of sympathetic constrictor nerves during arterial hypoxia.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The control of the circulation in skeletal muscle during arterial hypoxia in the rabbit

Chalmers

Korner²,

White³

1966

The Journal of Physiology

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“…The adrenal medulla can secrete catecholamines upon either nervous or humoral stimulation (39)(40)(41). The nervous mechanism is usually considered to be the more important one; Cannon, Linton, and Linton (42) showed in exercising dogs that catecholamines were not released from the adrenal medulla when the gland was denervated.…”

mentioning

confidence: 99%

Mechanisms Regulating the Cardiac Output Response to Cyanide Infusion, a Model of Hypoxia

Liang¹,

Huckabee²

1973

J. Clin. Invest.

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“…Previous analysis has shown that reflexly increased sympathetic nerve activity and adrenal medullary hormone secretion (mainly adrenaline in the rabbit) play a complementary part in the reflex maintenance of the arterial pressure after severe haemorrhage (Chalmers et al 1967a). The amount of adrenaline secretion after haemorrhage is high (Malmejac, 1964), and the increased sympathetic neural activity is probably also high. The present experiments support the view of a fairly generalized sympatho-adrenal discharge to the various regions maximal after haemorrhage but lasting for at least 4 hr.…”

Section: Methodsmentioning

confidence: 99%

“…Such a synergism could also account for the portal constriction. The initial increase in muscle vascular resistance and its subsequent decline to control values may be explained by initial potentiation of the effects of constrictor nerve activity by the ac-adrenergic constrictor action of adrenaline in view of the high rate of secretion of this hormone at this time (Celander, 1954;Malmejac, 1964), giving way to the opposing effects of constrictor nerve activity and the f8-adrenergic dilator action of smaller amounts of adrenaline as described in reflex control of this bed in arterial hypoxia (Chalmers et al 1966). The slight reflex effects, and preponderant vasodilatation of the skin vessels may be due to their relative insensitivity to adrenaline (Chalmers et al 1966) and the consequent opposing effects of neural activity and local dilator factors.…”

Section: Methodsmentioning

confidence: 99%

Effects of haemorrhage on the distribution of the peripheral blood flow in the rabbit

Chalmers

Korner²,

White³

1967

The Journal of Physiology

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SUMMARY1. The effects of bleeding unanaesthetized rabbits by 26% of their blood volume on the blood flow in the portal, renal, muscle and skin beds were investigated in normal animals, in animals without functioning autonomic effectors, and in animals with section of the carotid sinus and aortic nerves.2. In animals without functioning autonomic effectors there was progressive vasodilatation during the 4 hr following haemorrhage, which differed markedly in the different regional beds studied. The dilatation was greatest in the portal bed, followed by kidney and skin, but there was no significant change in the vascular resistance in muscle.3. In normal animals with intact reflexes the vascular resistance either increases or remains at control values, suggesting that reflex constrictor effects oppose locally acting dilator mechanisms. During the 4 hr following haemorrhage reflex vasoconstrictor effects were greatest in kidney, followed by muscle, portal bed and skin.4. In animals with section of the carotid sinus and aortic nerves reflex constrictor effects were absent in the portal, muscle and skin beds, but significant vasoconstriction was still evident in the renal bed, though of smaller magnitude than in normal animals. The results suggest that the arterial baroreceptors are a major source of reflex activity following haemorrhage, but that other reflexogenic zones contribute to the renal effects in normal animals.

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Activity of the Adrenal Medulla and its Regulation

Cited by 62 publications

References 0 publications

The control of the circulation in skeletal muscle during arterial hypoxia in the rabbit

The control of the circulation in skeletal muscle during arterial hypoxia in the rabbit

Mechanisms Regulating the Cardiac Output Response to Cyanide Infusion, a Model of Hypoxia

Effects of haemorrhage on the distribution of the peripheral blood flow in the rabbit

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