Increase in vasopressin concentration and cardiodepressant activity in the blood dialysates from the sella turcica during acute hypoxia.

OBJECTIVE

It was previously observed that infusion of angiotensin II, hypertonic saline and N-methyl-D-aspartic acid (NMDA) causes an increase in vasopressin and cardiodepressant factor release from the posterior pituitary lobe into the blood (Goraca 1998). The aim of present study was to investigate if the cardiodepressant factor and vasopressin are simultaneously released from the pituitary into the blood dialysate during acute hypoxia.

METHODS

The samples of dialysates of venous blood outflowing from the vicinity of cavernous sinus of the sella turcica were collected in anaesthetized rats. 30-min hypoxia was obtained by increasing the respiratory dead space. The concentration of vasopressin in blood dialysate was determined by radioimmunoassay, and cardiodepressant activity on spontaneously discharging pacemaker tissue of the right auricle of the right heart atrium.

RESULTS

Acute hypoxia caused simultaneously an increase in cardiodepressant activity and vasopressin concentration in the blood dialysate outflowing from the vicinity of cavernous sinus of the sella turcica.

CONCLUSIONS

These data suggest that cardiodepressant factor released together with vasopressin from the posterior pituitary lobe decrease the heart contraction rate and improves coronary circulation affected by vasopressin release.