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Biomedical subjects

A Berthelot

Publications and source records attributed to A Berthelot.

66 records · Page 4Linked to original sources
PubMed1978

Effect of parathyroidectomy on cardiovascular reactivity in rats with mineralocorticoid-induced hypertension.

Previous work has shown that parathyroidectomy protected Sprague-Dawley rats against mineralocorticoid hypertension. 2 In order to explain this protection, we studied vascular reactivity to noradrenaline and angiotensin II in several groups of rats with and without their parathyroid and thyroid glands. Work was performed in vagotomized, anaesthetized rats after ganglionic blockade with pentolinium, and atropine sulphate. 3 The reactivity to noradrenaline was significantly lower in parathyroidectomized rats, especially at the beginning of mineralocorticoid treatment. 4 Autotransplantation of parathyroid glands in thyroparathyroidectomized rats re-established normal cardiovascular reactivity and development of hypertension. 5 Cardiovascular reactivity to angiotensin II was not affected in parathyroidectomized rats and was lowered in thyroparathyroidectomized thyroxine-treated rats.

Angiotensin II↗
PubMed1978

Increase in urinary excretion of phosphates, hydroxyproline, and cAMP during acetate desoxycorticosterone + saline treatment in the rat.

We investigated the urinary excretion of phosphates, hydroxyproline, and cAMP in rats treated with desoxycorticosterone acetate (DOCA) associated with a hypersaline diet. We measured the three substances in groups with or without parathyroid or thyroid glands, or both. Urinary phosphate excretion increased greatly during the first weeks of treatment in normal rats and in rats autografted with parathyroids and lacking thyroid, and increased slightly in the groups without parathyroids. Hydroxyproline and cAMP had the same pattern; their excretion was greatest during week 2 of treatment in all groups, but these phenomena were more intense in animals with parathyroids. These fact support the conclusion that the parathyroid glands are stimulated during the start of mineralocorticoid-saline treatment.

Animals↗
PubMed1978

[Arterial blood pressure and high calcium diet in normal and mineralcorticoid (DOCA and sodium chloride hypertensive rats].

High calcium diet induces an hypertension lasting one week in normal rats. In mineralocorticoid treated rats (DOCA + NaCl), the same diet prevents for 10 weeks the increase of arterial blood pressure. Parathyroid activity (estimated by urinary cAMP) is decreased after the high calcium diet. These results confirm the role of the parathyroid glands in mineralocorticoid hypertension in the rat.

Animals↗
PubMed1977

[Calcium metabolism and mineralocorticoid-induced hypertension: effects of parathormone and exogenous thyrocalcitonin and of variations in dietary calcium and magnesium].

Physiological doses of parathyroid extract producing normal serum calcium level restore mineralocorticoid hypertension development in parathyroidectomized or thyroparathyroidectomized rats, supplemented with thyroid hormones. On the other hand, increased calcium or magnesium in dietary moderates hypertension development. Those results confirm the participation of parathyroids during mineralocorticoid hypertension.

Animals↗
PubMedDate not supplied

Central and peripheral alpha-adrenoceptor number and responsiveness after sinoaortic denervation in the rabbit.

The effects of bilateral sinoaortic denervation were examined in rabbits in vivo and in vitro. In the in vivo studies the effects of intravenous administration of the alpha-adrenoceptor agonists phenylephrine and guanabenz and the antagonists prazosin and phentolamine on mean arterial pressure, heart rate, and plasma catecholamine levels were investigated in intact sham-operated rabbits and after bilateral baroreceptor deafferentation. In in vitro studies the maximum number of prazosin and clonidine binding sites and their dissociation constants were investigated using radioligand binding techniques. Mean arterial pressure was labile and significantly elevated in the sinoaortic denervated rabbits. Heart rate and basal plasma noradrenaline were also raised, but plasma adrenaline and tissue noradrenaline levels were similar in intact and debuffered animals. alpha-Adrenoceptor antagonists were more effective at lowering mean arterial pressure in the sinoaortic-denervated animals. This was at least in part the result of a lack of compensatory changes in sympathetic activity and heart rate in these animals. Pressor responses to the alpha 1-adrenoceptor agonist and more markedly to the alpha 2-adrenoceptor selective agonist were increased after sinoaortic denervation. These changes could not be related to alteration in alpha 1- or alpha 2-receptor binding in either heart, spleen, or brain tissue as there was no change in number of binding sites or affinity.

Animals↗