Sympathetic and VIP-ergic control of calcium and bicarbonate transport in the feline gall bladder mucosa in vivo.
The regulation of calcium ion absorption by the gall bladder mucosa may be important for gall stone formation but this process is poorly understood. In this study performed in anaesthetized cats, the gail bladder lumen was perfused by a buffer equilibrated with 4% CO2 in air. During basal conditions, the pH and the [Ca2+] x [CO3(2-)] ion product decreased in the buffer when passing through the gall bladder lumen. The net absorption of calcium ions and fluid was significantly enhanced by stimulation of the splanchnic nerves. Intravenous infusion of vasoactive intestinal peptide (VIP) increased pH and the [Ca2+] x [CO3(2-)] ion product significantly in the buffer during the passage through the gall bladder lumen. Moreover, the basal fluid absorption was reversed to a net fluid secretion. In view of the presence of noradrenergic and VIP-immunoreactive nerve fibres in the gall bladder wall, and VIP-receptors on the gall bladder epithelial cells, the study suggests the existence of neural control mechanisms influencing the transport of Ca2+ by the gall bladder mucosa. These may be important to reduce potential calcium lithogenicity in the gall bladder lumen.
Nilsson
B
B
Department of Surgery, Sahlgrenska University Hospital, Göteborg, Sweden.
Delbro
D
D
Friman
S
S
Thune
A
A
Svanvik
J
J
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D001692:Biological Transport / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D002415:Cats; D005260:Female; D005704:Gallbladder / Q000378:metabolism*; D008297:Male; D013153:Splanchnic Nerves / Q000502:physiology*; D014660:Vasoactive Intestinal Peptide / Q000502:physiology*
D001639:Bicarbonates; D014660:Vasoactive Intestinal Peptide; D002118:Calcium