system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Anti-Inflammatory Agents, Non-Steroidal, Anti-Ulcer Agents, Aspirin, Gastric Acid, Gastric Mucosa, Histamine Antagonists, Histamine H1 Antagonists, Histamine H2 Antagonists, Hydrogen-Ion Concentration, Male, Omeprazole, Pentagastrin, Perfusion, Pyrilamine, Ranitidine, Rats, Rats, Sprague-Dawley, Stomach Ulcer.
user
Is pentagastrin gastroprotection against acid related to H2 receptor activation but not acid secretion? Context: Pentagastrin enhances gastric mucosal defense mechanisms against acid and protects the gastric mucosa from experimental injury. To investigate whether this gastroprotection is mediated by histamine receptors or occurs as a secondary effect of acid secretion stimulation. The effects of omeprazole (100 mumol/kg), ranitidine (20 mg/kg), and pyrilamine (10 mg/kg) on pentagastrin (80 micrograms/kg/h) induced gastroprotection against acidified aspirin injury were examined in a luminal pH controlled model. The effects of these compounds on pentagastrin enhanced gastroprotective mechanisms were investigated using intravital microscopy, in which intracellular pH of gastric surface cells (pH1), mucus gel thickness, gastric mucosal blood flow, and acid output were measured simultaneously. Pentagastrin protected rat gastric mucosa from acidified aspirin injury. This gastroprotection was abolished by ranitidine, but not omeprazole or pyrilamine. Pentagastrin induced a hyperaemic response to luminal acid challenge, increased mucus gel thickness, and elevated pHi during acid challenge. Ranitidine reversed these enhanced defence mechanisms, whereas omeprazole and pyrilamine preserved these effects.
assistant
These data indicate that pentagastrin associated gastroprotection and enhanced defence mechanisms against acid result mainly from activation of histamine H2 receptors, and not as an effect of the stimulation of acid secretion. Final Decision: yes