Immunohistochemical localization of carbonic anhydrase isoenzymes in salivary gland and intestine in adult and suckling pigs

Localizations of carbonic anhydrase isoenzymes (CA I, CA It and CA III) wer e investigated immunohistochemically in Me salivary glands and intestine of mature and suckling pigs. Carbonic anhydrase isoenzymes were not detected in the salivary glands of sucklings, but were present in the adult. Bicarbo nate ion in saliva might be important for the digestion of solid foods in m ature pigs, but unnecessary for the digestion of milk in sucklings. Express ions of CAI and CAII were detected strongly in the large intestine of the a dult and sucklings, and faintly only at duodenum in the small intestine. CA I and CA II isoenzymes in the large intestine may be involved, at least in part, in ion absorption and water metabolism during digestion and absorpti on of milk in suckling pigs. In addition, CA I and CA II expression in the duodenal villus enterocyte may support the process of bicarbonate absorptio n in the duodenum.