Amino acids were emitted from intravenous solutions for 8 hr, and enteral feedings were omitted for 6 hr to studies on 2 consecutive days prior. On day 1 basal acid output (BAO) was 28±5 μmoles/kg.hr, and post-pentagastrin (6 μg/kg, s.c.) maximal acid output (MAO) was 99±20 μmoles/kg.hr.
In contrast, fasted water snakes secreted gastric acid and intestinal base at rates similar to those of digesting snakes. We observed no difference between fasted and fed individuals for either species in gastric or intestinal transepithelial potential and conductance, with the exception of a significantly greater gastric transepithelial potential for fed pythons at the start of titration. Water snakes experienced no significant change in gastric or intestinal metabolism with feeding.
This gives the duodenum time to work on the chyme it has received before being loaded with more.
This tolerance does become a major problem for patients with massive hyper secretion of acid – as in the Zollinger-Ellison syndrome. Tolerance becomes a limiting factor and the control of acid secretion usually fails after some weeks of treatment. In this rare disease, control of acid secretion with a PPI should be the normal approach. When acid secretion is stimulated with histamine, the systemic adverse effects of histamine can be prevented by a conventional antihistamine drug without affecting acid secretion.
Soon, however, the acid and semi-digested fats in the duodenum trigger the enterogastric reflex. That is, the duodenum sends inhibitory signals to the stomach by way of the enteric nervous system, while also sending signals to the medulla that inhibit the vagal nuclei. This reduces vagal stimulation of the stomach and stimulates sympathetic neurons that send inhibitory signals to the stomach. Stretching of the duodenum (the first segment of the small intestine ) enhances gastric function via the vagal nerve, as the chyme causes the secretion of gastrin, which stimulates the stomach.
- While fasting, pythons cease gastric acid and intestinal base secretion, both of which are stimulated with feeding.
- At steady state, esomeprazole 20 mg q.d.
- Genetic ablation of ClC-2 resulted in reduced gastric gland region, reduced parietal cell number, reduced H/K ATPase, reduced tubulovesicles and reduced stimulated acid secretion.
Candidates include at least the molecular and cellular mechanisms underlying gastric acid production and intestinal base secretion, cellular growth, microvillus growth, nutrient transport and hydrolase activities. (2) How conserved with respect to phylogeny and/or feeding habits is the adaptive cascade of downregulation of GI function that results in a depression in tissue metabolism which accumulates in a reduce basal metabolism that enhances survival during prolonged fasts? We know that infrequently feeding snakes possess relatively low SMRs and that they downregulate intestinal performance following processing of a meal (Secor, 2005a; Ott and Secor, 2007). This study has shown for one infrequently feeding snake that there is a corresponding decrease in GI metabolism.
We found pythons to possess a significantly lower SMR and to experience a much larger postprandial metabolic response compared with water snakes. For fasted pythons, the downregulated GI tract was characterized by a lower metabolic rate. Feeding for pythons triggered gastric acid and intestinal base secretion and a matched increase in metabolic rate.
To ascertain the links between feeding habit, whole-animal metabolism, and GI function and metabolism, we measured postprandial and preprandial metabolic rates and gastric and intestinal acid-base secretion, epithelial conductance and oxygen consumption for the frequently feeding diamondback water snake (Nerodia rhombifer) and the infrequently feeding Burmese python (Python molurus). Independent of body mass, Burmese pythons possess a significantly lower standard metabolic rate and respond to feeding with a much larger metabolic response compared with water snakes. While fasting, pythons cease gastric acid and intestinal base secretion, both of which are stimulated with feeding.