Spontaneous and stimulated adrenocorticotropin and vasopressin pulsatile secretion in the pituitary venous effluent of the XXXX .

@entity1831 @entity1641 @entity5463 @entity1425 @entity935 @entity701 @entity2661 @entity1063
Plasma ACTH, @entity5463 ( @entity1831 ), and @entity2661 were measured at 5-min intervals in the pituitary venous effluent of the unanesthetized @entity1641 . Pulses of ACTH and AVP were found to be surprisingly brief (usually of less than 10-min duration) and frequent (averaging between 15-25 min). A highly significant relationship in the changes in concentration of these two hormones was demonstrated (P less than 0.0002) both at rest and after a mild hypoglycemic stimulus. Although there was also a significant correlation (P less than 0.005) between simultaneous plasma ACTH and AVP values the pulse amplitude ratio of AVP to ACTH showed a considerable variation. A rise in @entity701 appeared to have a greater suppressive effect on the amplitude of ACTH than AVP pulses. The gradient in hormonal concentration between pituitary effluent and jugular plasma was at times over 50-fold for ACTH, and 500-fold for AVP. A gradient was also found for @entity1425 , @entity1063 , and @entity935 . A highly significant correlation (P less than 0.005) was demonstrated between changes in @entity1063 , ACTH, and AVP concentrations, but no such relationship could be shown for @entity1425 and @entity935 . It is concluded that there is a close temporal relationship between changes in ACTH, AVP, and @entity1063 concentrations. Pulses of these hormones are greater in amplitude and more frequent than would have been suspected from sampling peripheral plasma. The variability in the pulse amplitude ratio of ACTH and AVP may suggest that other factors are affecting ACTH secretion. The ability to sample frequently for several hormones and to obtain a marked gradient in hormonal secretion between the pituitary venous effluent and jugular plasma suggest that the @entity1641 should provide an excellent animal model in which to study the regulation of hypothalamic and pituitary hormone secretion.
