Ontogenesis of Gastric Acid Secretion in Fetal Rat

Abstract

Pediatr. Res. 15: 921-925 (1981) corticosteroids gastric acid development stomach fetus The pH of gastric fluid was measured in rat fetuses during the ANIMALS last 3 days of gestation. On day 19, the gastric pH was close to neutral. During the night of day 20, the pH was clearly lowered Sherman rats, fed a coinmercial diet (U.A.R., France), were (6.11 k 0.15 units), this decrease becoming more marked on the used for this study. To obtain fetuses of known age, females were following day. At birth (day 22), just before the first feeding, the mated overnight. Gestation was detected by palpation 2 wk later; pH of gastric fluid reached the mean value of 2.98 k 0.14 units. the day after the night of mating was considered as day zero of This drop in gastric pH was concomitant with an increase in gestation. In this strain, delivery occurs in the night of day 21. chloride concentration whereas the gastric Pcoz remained constant. These results imply that in term rat fetuses, the gastric CHEMICAL rnucosa secretes fixed acid, very likely hydrochloride acid. Ontogenesis of Gastric Acid Secretion in Fetal RatBERNARDThe administration of acetazolamide (inhibitor of carbonic anhydrase) to 20-day-old fetuses did not suppress the spontaneous acidification of gastric fluid, although the enzyme activity was reduced by approximately 80%. Moreover, the gastric pH in acetazolamide-injected fetuses was markedly lower than in the noninjected littermates. The administration of NaCl solution (acetazolamide vehicle) had no effect on the carbonic anhydrase activity but clearly decreased the pH of gastric fluid. Thus, the drop of gastric pH produced by injection of acetazolamide or saline solution alone probably results from a stress effect of puncture.In fetuses from adrenalectomized, metopirone-treated mothers, the injection of NaCl solution no longer had effect on the pH of gastric fluid whereas triamcinolone injection produced a clear decrease in the gastric pH 3 hr later. SpeculationCorticosteroids could play an important role in the development of H+ generation processes in parietal cells during the fetal period of life.Electron microscopic studies have shown that in some mammals species, including man, parietal cells of the gastric mucosa begin to develop during intrauterine life (14,15,25). It has been observed that gastric acid secretion takes place before birth in guinea pig (28), lamb (16), and rabbit (30). Newborn human infants have an intragastric pH ranging from 5.5 to 7; this pH then strongly decreases by 4 to 5 hr of age (1, 13). As far as we know, there is Acetazolamide was purchased from Theraplix (Paris, France), and triamcinolone was purchased from Sigma Chemical Co. (Saint Louis, MO). Metopirone was a gift of the Ciba laboratory, (Basel, Switzerland). EXPERIMENTAL PROCEDURESPregnant rats were adrenalectomized under ether anaesthesia on day 16 of gestation and then received 10 mg metopirone by intraperitoneal injections twice a day until the time of sacrifice. Such treatment suppresses, or at least strongly reduces, th...

Development of sodium and chloride transport across fetal and newborn rat stomach in vitro.

“…113, Usine d'Aliments Rationnels, Villemoisson/Orge, France) and given water ad libitum. Fetuses of known age were obtained as previously described (Ducroc et al 1981;. In this strain, parturition occurs on day 22.…”

“…The transmural potential difference (PD), total ionic conductance (G) and short-circuit current (I,,) were measured as previouslv described (Ducroc et al 1981), using KCl-agar bridges, calomel electrodes, a high-impedance electrometer and a voltage-clamp device (F. C. Fastenow, Iowa University, IA. USA).…”

“…We previously established that on day 19 of gestation, before H+ secretion appears, fetal stomach maintained significant sodium-dependent but not chloride-dependent short-circuit current. In contrast, from day 20, when morphological differentiation of parietal cells is observed (Helander, 1969), active H+ secretion appears concomitantly with a significant increase in sodium-and chloride-dependent shortcircuit current, and a decrease in ionic conductance and passive permeability (Garzon, Ducroc & Geloso, 1981;Ducroc, Desjeux, Garzon, Onolfo & Geloso, 1981).…”

“…In this study, we examined unidirectional Na+ and Cl-fluxes across isolated fetal stomach on the 3 last days of gestation, a period for which the functional maturation of parietal cells is documented (Ducroc et al 1981), and across the stomachs of newborns 5 or 12 days old, when inhibition of acid secretion has been reported (Takeuchi et al 1981;Ackerman, 1982;Avril et al 1986). …”

Characteristics to Consider when Choosing an Animal Model for the Study of Lead Bioavailability

“…Measurements of pH of gastric contents have been used to detect acid secretion capacity but this technique is unable to pro.vide information about quantities of acid secreted over time or acid secretion set points (Garzon, 1982). Ussing chambers have been used as experimental techniques allowing for measurement of basal acid secretion and in vitro response to humoral stimuli (Ducro et al, 1981).…”