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  • Author or Editor: Anje G. Bauck x
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Abstract

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.

Open access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To examine effects of continuous rate infusion of lidocaine on transmural neutrophil infiltration in equine intestine subjected to manipulation only and remote to ischemic intestine.

ANIMALS 14 healthy horses.

PROCEDURES Ventral midline celiotomy was performed (time 0). Mild ischemia was induced in segments of jejunum and large colon. A 1-m segment of jejunum was manipulated by massaging the jejunal wall 10 times. Horses received lidocaine (n = 7) or saline (0.9% NaCl) solution (7) throughout anesthesia. Biopsy specimens were collected and used to assess tissue injury, neutrophil influx, cyclooxygenase expression, and hypoxia-inducible factor 1α (HIF-1α) expression at 0, 1, and 4 hours after manipulation and ischemia. Transepithelial resistance (TER) and mannitol flux were measured by use of Ussing chambers.

RESULTS Lidocaine did not consistently decrease neutrophil infiltration in ischemic, manipulated, or control tissues at 4 hours. Lidocaine significantly reduced circular muscle and overall scores for cyclooxygenase-2 expression in manipulated tissues. Manipulated tissues had significantly less HIF-1α expression at 4 hours than did control tissues. Mucosa from manipulated and control segments obtained at 4 hours had lower TER and greater mannitol flux than did control tissues at 0 hours. Lidocaine did not significantly decrease calprotectin expression. Severity of neutrophil infiltration was similar in control, ischemic, and manipulated tissues at 4 hours.

CONCLUSIONS AND CLINICAL RELEVANCE Manipulated jejunum did not have a significantly greater increase in neutrophil infiltration, compared with 4-hour control (nonmanipulated) jejunum remote to sites of manipulation, ischemia, and reperfusion. Lidocaine did not consistently reduce neutrophil infiltration in jejunum.

Full access
in American Journal of Veterinary Research