Plasma somatostatin and cholecystokinin levels in preterm infants and their mothers at birth.

Regulatory gut peptides play an important role in regulating the gastrointestinal tract. Our knowledge about the pattern of secretion and function of these peptides is scanty in preterm infants. Therefore, plasma somatostatin (SS) and cholecystokinin (CCK) levels were estimated just after birth in 65 mothers and 73 preterm infants (umbilical cord blood). The gestational age was 32 (24-36 median ranges) wk and birth weight 1900 (475-3350) g. The umbilical cord blood pH was 7.32 +/- 0.10 (mean +/- SD). After Sep-Pak-C18 semichromatography of plasma, SS and CCK were analyzed by RIA. Both plasma SS and CCK levels were significantly higher in infants than in mothers (SS = 14.5 +/- 12.4 versus 9.3 +/- 7.6 pmol/L; CCK = 11.6 +/- 7.4 versus 7.0 +/- 1.9 pmol/L). In appropriate for gestational age and small for gestational age infants' plasma levels of the two peptides were the same. They were also independent of sex, birth weight, gestational age, umbilical cord blood pH, or glucose level. In mothers, but not in infants, plasma SS levels were higher after vaginal delivery than after cesarean section. After multiple birth, newborn plasma SS, but not plasma CCK, was significantly lower than after single birth (9.1 +/- 7.7 versus 16.9 +/- 12.7 pmol/L).