Vertebrates are known to differ in their response of gastric acid secretion during periods of fasting, yet the reasons for these differences remain
unclear. Previously, continuous measurements of gastric pH in leopard sharks (Triakis semifasciata) had determined that acid secretion in this
species is continuous. In order to determine if maintaining an empty acidic stomach may reduce digestion time of a subsequent meal, a simple
descriptive model based on acid secretion rates was developed. In vivo gastric acid secretion rates were measured using an auto-titration technique.
Acid secretion rates were pH dependent, with rates of 6.1±3.0 (±1 SD) mmol/h when gastric pH was >2.5, and 1.7±0.8 mmol/h when pH was
2.0–2.5. Analysis by Western blots suggests that pepsin secretion occurs within 1 h of feeding, and that there is a de-coupling of acid and pepsin
secretion. The model estimates that digestion time can be reduced by 5.7±1.3 h and pepsin activity increased by 10–100% during that time if the
stomach is acidic before feeding. Gastric acid secretion during fasting is hypothesized to reduce digestion time of a subsequent meal in frequently
feeding sharks, which may be advantageous for exploiting resources that are spatially and temporally unpredictable.
© 2006 Elsevier Inc. All rights reserved.
Vertebrates are known to differ in their response of gastric acid secretion during periods of fasting, yet the reasons for these differences remainunclear. Previously, continuous measurements of gastric pH in leopard sharks (Triakis semifasciata) had determined that acid secretion in thisspecies is continuous. In order to determine if maintaining an empty acidic stomach may reduce digestion time of a subsequent meal, a simpledescriptive model based on acid secretion rates was developed. In vivo gastric acid secretion rates were measured using an auto-titration technique.Acid secretion rates were pH dependent, with rates of 6.1±3.0 (±1 SD) mmol/h when gastric pH was >2.5, and 1.7±0.8 mmol/h when pH was2.0–2.5. Analysis by Western blots suggests that pepsin secretion occurs within 1 h of feeding, and that there is a de-coupling of acid and pepsinsecretion. The model estimates that digestion time can be reduced by 5.7±1.3 h and pepsin activity increased by 10–100% during that time if thestomach is acidic before feeding. Gastric acid secretion during fasting is hypothesized to reduce digestion time of a subsequent meal in frequentlyfeeding sharks, which may be advantageous for exploiting resources that are spatially and temporally unpredictable.© 2006 Elsevier Inc. All rights reserved.
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