[Studies on the mechanism of blood pressure variability].

Blood pressure variability has been known in the cardiovascular clinic for a long time. The mechanisms of the variations are largely unknown; it was the aim of the present work to approach this question. In a first group of studies, the role of the adrenergic receptors was examined. The results have shown that the adrenergic system does not play an important role in this phenomenon as administration of beta and of alpha blocking agents is unable to diminish the amplitude of the blood pressure variations; this was confirmed by other studies showing no correlation between blood pressure variability and the response to sympathetic function tests. However, there was a positive correlation with the level of blood pressure. In a second part, the role of the cholinergic system was investigated; atropine was found to diminish, both in dogs as in men, the amplitude of blood pressure variability. No decrease of blood pressure variability was seen with calcium antagonists. Thus, blood pressure variability is depending on the level of blood pressure and cholinergic activity; since these mechanisms only explain part of blood pressure variability, further research will be needed to unravel this challenging question.