These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: [Intracellular mechanism of potentiating interaction of histaminergic and muscarinic receptors in rabbit parietal cells].
    Author: Oikawa Y.
    Journal: Hokkaido Igaku Zasshi; 1993 Sep; 68(5):683-93. PubMed ID: 8225175.
    Abstract:
    Intracellular mechanisms of receptor-mediated acid secretion and potentiating interactions of receptors were explored in isolated gastric glands obtained from the stomach of New Zealand White rabbits. Intracellular free calcium concentration ([Ca2+]i) was measured by a digitized video-image analysis with a dual-wavelength excitation microspectrofluorometry in fura-2 loaded parietal cells, and acid secretion was determined in parallel experiments by monitoring the accumulation of [14C] aminopyrine (AP) in suspension of isolated glands. Histamine and carbachol stimulated acid secretion and increased [Ca2+]i in a concentration-dependent manner. The concentration-response curve for the acid producing effect of carbachol was overlapped by that for the [Ca2+]i-increasing effect. However, the concentration-response curve for the [Ca2+]i-increasing effect of histamine was shifted by approximately one order from that for the acid-producing effect, indicating that a low concentration of histamine can also stimulate acid secretion without [Ca2+]i increase in the rabbit parietal cells. Cimetidine, a H2-blocker, inhibited the histamine-induced acid secretion and [Ca2+]i increase competitively, and those responses induced by carbachol non-competitively. Carbachol at a concentration of 10(-3)M did not affect the histamine concentration of solution containing isolated gastric glands. Neither 10(-6)M 3-isobutyl-1-methyl-xanthine (IBMX) nor 3 x 10(-5)M dibutyryl adenosine 3',5'-cyclic monophosphate (dbcAMP) affected AP uptake and [Ca2+]i per se. However, these agents significantly potentiated the carbachol-induced acid secretion and [Ca2+]i increase. These results suggest that tonic stimulation of H2-receptors by a small amount of endogenous histamine potentiates the cholinergic acid secretion and [Ca2+]i increase. Parietal cells preconditioned by a small increase in intracellular cAMP may easily increase [Ca2+]i and acid secretion in response to cholinergic stimulation.
    [Abstract] [Full Text] [Related] [New Search]