High Pressure Liquid Chromatographic Separation of an Oxytocin⁄Arginine Vasotocin-Like Peptide from the Plasma of Patients with Chronic Renal Failure*

Abstract

Levels of a novel oxytocin (OT)- and arginine vasotocin (AVT)-like peptide detected by one antiserum to OT (Pitt Ab-1) and one antiserum to AVT (Tor AVT) were recently found to rise in human plasma in response to administration of estrogen. The novel peptide rose in parallel with the estrogen-stimulated neurophysin (ESN). The mean level (+/- SEM) of ESN in plasma of 11 individuals with altered renal function (nondialyzed) was significantly higher than the level in individuals with normal renal function (4.2 +/- 0.9 vs. 1.1 +/- 0.04 ng/ml; P less than 0.01). In patients treated with hemo- or peritoneal dialysis, mean (+/- SEM) levels of ESN were 18.1 +/- 3.2 and 16.8 +/- 3.7 ng/ml, respectively. Levels of estradiol and estrone were not elevated and did not correlate with high levels of ESN. Levels of OT Pitt Ab-1, AVT, and ESN immunoreactivity were measured in plasma form nine patients undergoing hemodialysis and eight patients undergoing peritoneal dialysis. Mean (+/- SEM) levels of all three peptides were elevated (12.9 +/- 1.5 microU/ml, 32.1 +/- 6.7 pg/ml, and 13.5 +/- 4.0 ng/ml, respectively). ESN was significantly correlated with OT Pitt Ab-1 and AVT (R2 = 0.80; P less than 0.001). Plasma samples from the same patients were pooled, treated, and separated by reverse phase HPLC. The plasma contained a peak of immunoreactivity detected by Pitt Ab-1 and Tor AVT Ab. The position of the material was distinct from that of synthetic OT, AVT, or AVP and corresponded to the position of the novel OT-like peptide found in plasma of individuals given estrogen. The findings support parallel secretion of the OT-like peptide with ESN and represent the first disease state characterized by high levels of this OT- and AVT-like peptide.

Circulating Immunoreactive Oxytocin During the Human Menstrual Cycle Comes From the Pituitary and Is Estradiol Dependent*

“…Our ability to measure very f-t-f-f-A 10 11 12 13 low concentrations of OT in serum contributed to this result. Our high performance liquid chromatographic analysis revealed no evidence of OT-like peptides distinct from OT, which other workers have found in the serum of patients receiving oral contraceptive steroids or in renal failure (14,15). Our patients received replacement therapy with E 2 rather than synthetic steroids, which might explain the absence of OT-like peptides in them.…”

Arginine Vasopressin (AVP) and AVP-Like Immunoreactivity in Peripheral Tissues

“…Finally, Amico et al have described a novel ir-AVT/ OT-like activity in the plasma of patients with chronic renal failure (123) or after estrogen administration (124). This activity was identified by a battery of antisera with varying specificities for AVT, OT, and AVP and did not have the same retention time as any of these nonapeptide standards on HPLC.…”

Oxytocin in the human--regulation of derivations and destinations

“…The enzymes which catalyse the formation of the forms may contribute to modulation of biological activities (15). One form (a little larger than native oxytocin) is induced by oestrogen and detected in the peripheral circulation and observed in patients with end-stage renal failure, suggesting one reason for its detection might be related to lowered clearance (94).…”