HIonensekretion

HIonensekretion, sometimes described as H+-ion secretion or hydrogen ion secretion, denotes the active transport of hydrogen ions across epithelial or cellular membranes into luminal spaces or the extracellular fluid. The term is not widely established as a stand-alone entry in standard physiology, but it is commonly discussed as part of the broader topics of ion secretion and proton transport. It plays a central role in acid-base balance across several organ systems.

Mechanistically, HIonensekretion relies on proton pumps that move H+ against electrochemical gradients. This includes H+-ATPases (notably V-type pumps in some epithelia and the H+/K+-ATPase in gastric parietal cells), often operating in concert with bicarbonate transporters and chloride carriers to maintain electroneutrality and intracellular pH. The exact transporter complement is tissue-specific.

Regulation varies by organ. Gastric H+-secretion is stimulated by gastrin, histamine, and acetylcholine and inhibited by somatostatin. In the kidney, distal nephron segments increase H+ secretion in response to acidosis and aldosterone, mediated by H+-ATPases and H+/K+-ATPases, as part of systemic acid-base homeostasis.

Physiological roles include luminal acidification in digestion, renal acid excretion, and mucosal pH regulation in the gut. Dysregulation can contribute to disorders of acid-base balance, such as renal tubular acidosis, or to altered digestive function. Pharmacological modulation of H+-secretion, for example with proton pump inhibitors, can affect pH and mineral balance.

Measurement and study rely on pH monitoring, transepithelial potential differences, ion flux assays, and molecular characterization of proton-transport proteins. See also acid-base homeostasis, proton pumps, gastric parietal cells, and renal acid secretion.