H+ BACK DIFFUSION STIMULATING GASTRIC-MUCOSAL BLOOD-FLOW IN THE RABBIT FUNDUS

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 89  (2) , 232-236
Abstract
The effect of barrier breakers on gastric mucosal blood flow (MBF) is disputed, but the influence of acid back diffusion was never studied. In anesthetized New Zealand white rabbits, intramural pH (pHi) and gastric MBF were measured with an Sb microelectrode and with radioactive microspheres (51Cr, 85Cr, 141Ce), respectively. Innervated fundic pouches were perfused with solutions of varying [H+] at 37.degree. C. In the rabbit back flux of H+ is linearly dependent on luminal [H+] and a direct positive linear correlation was found between luminal [H+] and MBF (r = 0.97 P < 0.001); pHi remained unchanged up to liminal [H+] of 80 mM. The usual 80% increase in MBF induced by 80 mM HCl was prevented by pretreatment with vasopressin, which decreased pHi and caused gross ulceration. Without vasopressin [H+] of 120 mM HCl produced gross mucosal ulceration and a decrease in MBF and pH. Back diffusion of H+ apparently influences MBF in the rabbit. There is an increasing MBF caused by increasing luminal [H+] up to 80 mM, beyond which MBF decreases. When the balance between back diffusion and MBF is distrubed by a vasoconstrictor or a high luminal [H+], pHi decreases and gross ulceration occurs.