Release of vasopressin, cortisol and beta-endorphin in tetraplegic subjects in response to head-up tilt.

Plasma levels of beta-endorphin, vasopressin and cortisol during head-up tilt were measured in tetraplegic patients and in normal healthy subjects. In tetraplegic patients rapid tilt from the horizontal to 30 degrees or 60 degrees head-up induced orthostatic hypotension and increased plasma levels of cortisol, beta-endorphin and vasopressin. In control subjects head-up tilt failed to alter plasma levels of these hormones. These data show that the head-up position in tetraplegics causes various endocrine reactions.