Helodermin and islet hormone release in isolated rat pancreas.

The effect of helodermin (1,10,100 pmol/L), a new member of the VIP/secretin/glucagon peptide family, was investigated in glucose- (10 mmol/L) and arginine- (10 mmol/L) induced insulin, glucagon, and somatostatin secretion from the isolated perfused rat pancreas. Helodermin stimulated the somatostatin release in a concentration-dependent manner during the first (controls, 100%; 1 pmol/L, 113%, ns; 10 pmol/L, 175%, p less than 0.05; 100 pmol/L, 233%, p less than 0.05) and the second secretion phases (controls, 100%; 1 pmol/L, 117%, ns; 10 pmol/L, 210%, p less than 0.05; 100 pmol/L, 362%, p less than 0.05). There was a biphasic glucagon response with an inhibition during the first phase (controls, 100%; 1 pmol/L, 92%; 10 pmol/L, 63%, p less than 0.05; 100 pmol/L, 52%, p less than 0.05%) and a stimulation during the second phase (controls, 100%; 1 pmol/L, 117%, ns; 10 pmol/L, 210%, p less than 0.05; 100 pmol/L, 362%, p less than 0.05). Helodermin had weak stimulatory effects on pancreatic beta cells with a maximum at 10 pmol/L (first phase: controls, 100%; 1 pmol/L, 96%, ns; 10 pmol/L, 148%, p less than 0.05; 100 pmol/L, 136%, ns; second phase: controls, 100%; 1 pmol/L, 104%, ns; 10 pmol/L, 170%, p less than 0.05; 100 pmol/L, 136%, ns).