The concentrations of immunoreactive gastrin in serum from portal and peripheral venous blood were determined in 10 patients with indwelling portal catheters before and after feeding. No significant differences were found between the gastrin concentrations in portal and peripheral serum. Gel filtration studies of serum did not reveal any differences between the gastrin components of portal and peripheral venous serum. Since neither the concentrations of immunoreactive gastrin nor the four gastrin components differed between portal and peripheral serum it is suggested that the liver is without effect on gastrin metabolism.

Aged↗

PubMed1973

Gel filtration studies on immunoreactive gastrin in serum from Zollinger-Ellison patients.

Sera from 15 patients with the Zollinger-Ellison syndrome were subjected to gel filtration on Sephadex G-50 superfine columns (10 x 2000 mm). The concentration of gastrin in the effluent was determined by a sensitive radioimmunoassay. Immunoreactive gastrin was eluted in four components in 14 sera. (1) Component I, eluted in the same position as proinsulin, constituted 9.7 +/- 1.2 (mean +/- SEM)% of the total immunoreactivity. (2) Component II (;big gastrin') eluted between proinsulin and insulin constituted 57.8 +/- 4.1% (mean +/- SEM) of immunoreactive gastrin. In three sera with the highest concentration of gastrin, component II appeared biphasic. (3) Component III (;little gastrin') was distributed in two peaks; the first one eluted in the same position as the heptadecapeptide gastrin II made up 17.4 +/- 2.7 (mean +/- SEM)% of the total immunoreactivity; the second one eluted in the same position as gastrin I constituted 9.5 +/- 1.3 (mean +/- SEM)%. (4) Component IV (;minigastrin') was eluted immediately before the salt peak and constituted 5.6 +/- 1.4 (mean +/- SEM)%. In one serum only components I and II were present. After incubation with trypsin all immunoreactivity in components I and II was converted to heptadecapeptide-like gastrins.The findings suggest that immunoreactive gastrin in serum from Zollinger-Ellison patients is circulating in at least four components of different molecular size.

Chromatography, Ion Exchange↗

PubMed1973

The effect of gastrin on basal- and glucose-stimulated insulin secretion in man.

The effect of gastrin on basal- and glucose-stimulated insulin secretion was studied in 32 normal, young subjects. The concentration of gastrin and insulin in serum was measured radioimmunochemically. Maximal physiologic limit for the concentration of gastrin in serum was of the order of 160 pmol per liter as observed during a protein-rich meal. Oral ingestion of 50 g glucose produced a small gastrin response from 28+/-3 to 39+/-5 pmol per liter (mean +/-SEM, P < 0.01). Intravenous injection or prolonged infusion of gastrin increased the concentration of insulin in peripheral venous blood to a maximum within 2 min followed by a decline to basal levels after a further 10 min. The minimum dose required to induce a significant insulin response (31.2 ng gastrin per kg) increased the gastrin level in serum above the physiologic range. Maximum effect was obtained with 500 ng gastrin per kg. When 15.6 ng (7.1 pmol) gastrin per kg body weight and 25 g glucose were injected simultaneously, the glucose-induced insulin response was potentiated (from 2.32+/-0.33 to 4.33+/-0.98 nmol per liter per 20 min, P < 0.02), even though gastrin concentrations only increased to 71.2+/-6.6 pmol per liter. No effect, however, was noted on glucose disposal. 15.6 ng gastrin per kg given i.v. 30 min before an i.v. glucose tolerance test was without significant effect on the insulin response. The results indicate that gastrin can stimulate a rapid and short-lived release of insulin. In physiologic concentrations gastrin potentiates the glucose-stimulated insulin secretion and is without effect on basal insulin secretion. A small release of gastrin during oral glucose ingestion may to a limited extent contribute to the nonglycemic insulin secretion. During protein ingestion, gastrin probably stimulates insulin secretion significantly.

Adult↗

PubMed1973