Adrenalectomy in rats depresses hypoxic pulmonary vasoconstriction in vitro but does not attenuate the pulmonary hypertension of chronic hypoxia (part 12)

21 Aug
2012

 In the monocrotaline experimental model of pulmonary hypertension, vascular wall damage is probably the most important causative factor. The absence of a protective effect of glucocorticoids may be one explanation for why hypoxic pulmonary hypertension was not attenuated after adrenalectomy, in spite of the described in vitro inhibition of acute hypoxic pulmonary vasoconstriction. The different experimental conditions used in the present experiments of acute and chronic hypoxia must also be considered. The first experiment was in vitro (isolated perfused lungs), the second in intact anesthetized rats. In adrenalectomized rats studied in vivo, pulmonary artery blood pressure increased in acute hypoxia similarly to controls.However, this does not necessarily mean that their hypoxic vasoconstriction did not differ. We did not measure lung blood flow. Reports of hypoxic pulmonary vasoconstriction after adrenalectomy in intact animals are scarce and contradictory. Wang and Wang found no effect of adrenalectomy in rats on the increase in pulmonary vascular resistance induced by inhalation hypoxia. Shirai and coworkers , however, found by direct x-ray measurements of the diameter of peripheral pulmonary arteries in the intact cat that, after adrenalectomy and ganglion blockade with hexamethonium bromide, vasoconstrictions induced by inhalation hypoxia were substantially increased. The possibility that the observed effect of glucocorticoids is specific for in vitro conditions is also supported by the finding that depression of vascular reactivity to hypoxia in lungs isolated from ad-renalectomized rats was reversed by angiotensin II. You will always find cialis super active online pharmacy buy now, shopping online with pleasure every time.

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