Posted by Larry Hoover on May 24, 2003, at 13:23:58
In reply to question for Larry Hoover, posted by Kari on May 24, 2003, at 12:27:42
> Hi Larry,
>
> I was wondering if calcium and magnesium taken in citrate form can cause excessive stomach acidity. Does this sound logical?
>
> Thanks,
> Kari.Geez, I shoulda looked before I answered....
There is a mechanism for that happening, but I'd bet you could reduce the effect by using the supplement with meals.
J Biol Chem 2001 Oct 26;276(43):39549-52
The stomach divalent ion-sensing receptor scar is a modulator of gastric acid secretion.Geibel JP, Wagner CA, Caroppo R, Qureshi I, Gloeckner J, Manuelidis L, Kirchhoff P, Radebold K.
Department of Surgery, Yale University School of Medicine, New Haven, CT 06511, USA. John.Geibel@yale.edu
Divalent cation receptors have recently been identified in a wide variety of tissues and organs, yet their exact function remains controversial. We have previously identified a member of this receptor family in the stomach and have demonstrated that it is localized to the parietal cell, the acid secretory cell of the gastric gland. The activation of acid secretion has been classically defined as being regulated by two pathways: a neuronal pathway (mediated by acetylcholine) and an endocrine pathway (mediated by gastrin and histamine). Here, we identified a novel pathway modulating gastric acid secretion through the stomach calcium-sensing receptor (SCAR) located on the basolateral membrane of gastric parietal cells. Activation of SCAR in the intact rat gastric gland by divalent cations (Ca(2+) or Mg(2+)) or by the potent stimulator gadolinium (Gd(3+)) led to an increase in the rate of acid secretion through the apical H+,K+ -ATPase. Gd(3+) was able to activate acid secretion through the omeprazole-sensitive H+,K+ -ATPase even in the absence of the classical stimulator histamine. In contrast, inhibition of SCAR by reduction of extracellular cations abolished the stimulatory effect of histamine on gastric acid secretion, providing evidence for the regulation of the proton secretory transport protein by the receptor. These studies present the first example of a member of the divalent cation receptors modulating a plasma membrane transport protein and may lead to new insights into the regulation of gastric acid secretion.
poster:Larry Hoover
thread:228853
URL: http://www.dr-bob.org/babble/20030520/msgs/228860.html