{'fraction_non_alphanumeric': 0.03476946334089191, 'fraction_numerical': 0.015117157974300832, 'mean_word_length': 4.382113821138211, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Mechanisms of bicarbonate secretion in the equine colon ex vivo.

OBJECTIVE
To examine bicarbonate (HCO3-) secretion ex vivo in the equine large colon to determine any differences between the right dorsal colon (RDC) and right ventral colon (RVC). The effect of phenylbutazone (PBZ) on HCO3- secretion was examined in the RDC.


ANIMALS
14 healthy horses.


PROCEDURES
In anesthetized horses (n = 10), segments of mucosa from RDC and RVC were harvested to measure HCO3- secretion ex vivo with the pH Stat method. The effect of PBZ on HCO3- secretion in the RDC was studied in 4 additional horses.


RESULTS
Three distinct mechanisms of HCO3- secretion previously described in a murine model were confirmed in the equine colon. The RDC had a greater capacity for electrogenic, Cl--independent HCO3- secretion than the RVC (P = 0.04). In the RDC, all HCO3- secretion was decreased by PBZ (P < 0.02) but was not studied in the RVC because of low baseline secretion.


CLINICAL RELEVANCE
Secretion of HCO3- by the RDC could play a pivotal role in equine colon physiology, because intense microbial fermentation in this site could require HCO3- secretion to buffer short-chain fatty acids. Inhibition of this secretion by PBZ could interfere with mucosal buffering and predispose to changes associated with right dorsal colitis.