[The effect of morphine and opiate receptor agonists on arterial pressure and the bioelectrical activity of the renal nerve during stimulation of the midbrain central gray substance].

It has been demonstrated in experiments on unrestrained and unanesthetized curarized cats that periaqueductal gray matter stimulation produce sympathetic-activating action, raise arterial pressure and heart rate, but at the same time is not effective enough to suppress the nociceptive shifts of haemodynamic reactions. Opioid mechanisms of spinal cord plays an essential role in sympathetic-activating action of periaqueductal gray matter. It is suggested that the influence of antinociceptive areas of the brain stem on sympathetic haemodynamic regulation is one of the causes of resistance of nociceptive haemodynamic reactions to narcotic analgetics.