Luminal osmolarity downregulates gene expression of Na+/H+ exchanger (NHE3) in rat colon mucosa.

Water-coupled Na&sup+ absorption in the colon is mediated principally by Na+/H+ exchange (isoforms NHE2 and NHE3). To determine whether luminal ion composition or osmolarity influences NHE expression in colon mucosa, two groups (n = 6 in each) of adult male Sprague-Dawley rats underwent sham laparotomy or loop ileostomy. In these studies, diversion did not markedly alter mRNA levels for NHE2, NHE3, or Na+/K+, at 8 or 21 days, indicating that loss of luminal volume does not alter NHE gene expression. To evaluate the effects of specific luminal components, we infused equal volumes of half-normal (154 mOsm) or iso-osmolar (308 mOsm) solutions of saline and mannitol into the diverted colon. All solutions elicited significant (45% to 60%; P <0.05) decreases in mRNA levels for NHE3, with iso-osmolar mannitol eliciting the greatest changes. Decreases in NHE2 and Na+/K+ mRNA levels were observed following these infusions but were not as marked as the changes for NHE3. These findings suggest that (1) loss of luminal Na+ is not, in itself, a signal that regulates NHE expression and (2) infusion of any solute, including Na+ itself, provides a signal to downregulate expression of NHE3 in colon mucosa.

Symptomatic gallstones in patients with spinal cord injury.

Patients with spinal cord injury (SCI) have an increased prevalence of cholelithiasis. The goal of this study was to clarify the presentation and management of symptomatic gallstone disease in patients with SCI. We performed a retrospective study of presentation of gallstone complications in patients with SCI who underwent cholecystectomy for complications of gallstone disease. The West Roxbury Veterans Administration Medical Center SCI registry (605 patients) was searched for patients who had undergone cholecystectomy more than 1 year after SCI (35 patients). Gallbladder disease profiles for the 35 patients undergoing cholecystectomy for complications of gallstone disease were prepared, including demographics, clinical presentation, diagnostic studies, operative and pathologic findings, and postoperative complications. All patients were white. Thirty-four were male and the mean age was 50 years (range 35 to 65 years). The majority of patients (66%) complained of right upper quadrant abdominal pain, even those patients with SCI at high (i.e., cervical) levels. Of the 35 patients in our study group, 22 (63%) had biliary colic and chronic cholecystitis, nine (26%) had acute cholecystitis (gangrenous cholecystitis in two), two (6%) had choledocholithiasis symptoms or cholangitis, and two (6%) had gallstone pancreatitis. Major perioperative morbidity occurred in two (6%) of the 35 patients (pulmonary embolus; intraoperative hemorrhage), and there were no deaths. In the great majority of patients with SCI, cholelithiasis presents with chronic pain and not with life-threatening complications. Our findings suggest that presentation is no more acute in patients with SCI than in the general population. Characteristic symptoms and signs are not necessarily obscured by SCI injury, regardless of the level.