title: Persistence of circadian rhythms in gastric acid, gastrin, and pancreatic polypeptide secretions despite loss of cortisol and body temperature rhythms in man under stress.
abstract: During organic stress, severe dysfunctions of fundamental biological phenomena, such as modification of vagal tone, have been described. These dysfunctions could induce changes in the rhythm of acid secretion and/or its hormonal control. We therefore analyzed the effects of acute respiratory failure on the 24 h variations in intragastric pH, serum gastrin, and pancreatic polypeptide levels, taken as a marker of vagal tone. Body temperature and plasma cortisol circadian rhythms were used as marker rhythms. Twelve patients with chronic obstructive pulmonary disease complicated with acute respiratory failure were studied before and during continuous enteral nutrition; half of the patients received ranitidine, a H2 blocker. During the 3 days of the study, intragastric pH was below 2.5 for only one third of the time. No difference was observed between the placebo and the ranitidine groups. Plasma pancreatic polypeptide was within normal ranges despite increased cortisol levels. Gastrin levels reflected changes in intragastric pH over the 24 h time frame and were noted to increase during ranitidine and enteral nutrition. Despite the loss of cortisol and body temperature circadian rhythmicity all throughout the study, circadian rhythms were maintained or restored during the different therapeutic regimens for intragastric pH, serum gastrin, and pancreatic polypeptide levels. Moreover, an ultradian rhythm for gastrin before any treatment, a circadian rhythm for intragastric pH on enteral nutrition, a circadian rhythm for intragastric pH, plasma gastrin and plasma pancreatic polypeptide on ranitidine regimen were observed. Thus during acute respiratory failure, certain physiological circadian rhythms persisted despite the disappearance of "marker" rhythms. Furthermore, these rhythms for digestive secretions could be pharmacologically restored.
mesh_terms: D000208:Acute Disease; D000368:Aged; D001831:Body Temperature; D002940:Circadian Rhythm; D004311:Double-Blind Method; D004750:Enteral Nutrition; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D005745:Gastric Acidity Determination; D005755:Gastrins / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010191:Pancreatic Polypeptide / Q000378:metabolism*; D011897:Random Allocation; D011899:Ranitidine / Q000627:therapeutic use; D012131:Respiratory Insufficiency / Q000097:blood*; D013312:Stress, Physiological / Q000097:blood*
chemical_list: D005755:Gastrins; D010191:Pancreatic Polypeptide; D011899:Ranitidine; D006854:Hydrocortisone