Vasopressin, vasopressin fragments and a C-terminal peptide of the vasopressin precursor share cardiovascular effects when microinjected into the nucleus tractus solitarii.

Arginine-vasopressin (VP), the VP fragments VP-(1-8), [pGlu4,Cyt6]VP-(4-9) and -(4-8), and a fragment of the C-terminal glycopeptide of the VP precursor [CPP-(22-39)] decreased blood pressure and heart rate in anesthetized rats when microinjected bilaterally into the nucleus tractus solitarii (NTS). The magnitude of the effect was similar at doses of 20 pg, except for VP-(1-8) which required about 500 pg. The strongest decrease in blood pressure and heart rate was observed with 100 pg VP. Higher doses of other peptides either were ineffective [CPP-(22-39)] or increased blood pressure [( pGlu4,Cyt6]VP-(4-9) and -(4-8)). VP metabolites thus may participate in the control of cardiovascular functions exerted by VP. The effect of CPP-(22-39) indicates that the C-terminal glycopeptide of the VP precursor contains biological activity, which may support the cardiovascular action of VP in the NTS.