Hormonal and metabolic effects of near physiological increase of plasma immunoreactive somatostatin 14.

The possibility that somatostatin 14 (SRIF) may exert true endocrine actions in man was tested by investigating the hormonal and metabolic effects of the peptide infused for 80 min at rates of 36.5, 73, and 146 pmol kg-1 h-1 in six healthy subjects who fasted overnight. These three doses increased the level of plasma SRIF-like immunoreactivity in the range of concentrations recorded postprandially with the same assay system. These low SRIF infusion rates decreased insulinemia and to a lesser extent glucagonemia, and increased glucosemia and ketonemia. Both the reduction of insulin and the increase of glucosemia were significantly related to the increase of plasma SRIF-like immunoreactivity. All parameters returned to control values upon discontinuing the peptide infusion. This study suggests that SRIF may have an endocrine role in man and that such low dose, short time SRIF infusions could exert metabolic effects different from those of larger, probably pharmacological, infusion rates.