Hypergravitation and sympatho-adrenergic reactivity

The cardiac frequency and adrenal and urinary catecholamine content were investigated on 10-minutes centrifuged rats (+6 Gz). It was found that the heart responds in an individual manner, with a general tendency to tachycardia. Under the same conditions after 1 1/2 minute the adrenal noradrenaline response was absent, after 3' and 6' the adrenal noradrenaline content was augmented and the adrenaline one diminished, and after 10' the response vanished. Hypergravitation does not change the urinary noradrenaline elimination collected after 10 minutes of centrifugation, but that of adrenaline is augmented in one of the two explored animal groups. The difference between the two groups may be explained by the great individual variations, as results from the cardial frequency (appreciated by teleelectrocardiogram). The environmental stress produces similar but more reduced catecholamine modifications.