Background/Aims: Several studies have assessed the effect of cool temperature on colonic peristalsis. Transient receptor potential melastatin 8 (TRPM8) is a temperature-sensitive ion channel activated by mild cooling expressed in the colon. We examined the antispasmodic effect of cool temperature on colonic peristalsis in a prospective, randomized, single-blind trial and based on the video imaging and intraluminal pressure of the proximal colon in rats and TRPM8-deficient mice. Methods: In the clinical trial, we randomly assigned a total of 94 patients scheduled to undergo colonoscopy to 2 groups: the mildly cool water (n = 47) and control (n = 47) groups. We used 20 mL of 15°C water for the mildly cool water. The primary outcome was the proportion of subjects with improved peristalsis after treatment. In the rodent proximal colon, we evaluated the intraluminal pressure and performed video imaging of the rodent proximal colon with cool water administration into the colonic lumen. Clinical trial registry website (Trial No. UMIN-CTR; UMIN000030725). Results: In the randomized controlled trial, after treatment, the proportion of subjects with no peristalsis with cool water was significantly higher than that in the placebo group (44.7% vs 23.4%; P < 0.05). In the rodent colon model, cool temperature water was associated with a significant decrease in colonic peristalsis through its suppression of the ratio of peak frequency (P < 0.05). Cool temperaturetreated TRPM8-deficient mice did not show a reduction in colonic peristalsis compared with wild-type mice. Conclusion For the first time, this study demonstrates that cool temperature-dependent suppression of colonic peristalsis may be associated with TRPM8 activation.

A 36-year-old man underwent direct closure of an atrial septal defect through median sternotomy at the age of 14. He also underwent a mitral valve replacement with tricuspid annuloplasty using the same approach at the age of 18. The patient also presented with pretibial edema and congestive liver disease at the age of 27 and the pretibial edema progressed at the age of 35. Hypoalbuminemia (TP ; 3.6 g/dl, Alb ; 1.6 g/dl) was also observed. Further examinations were performed, which revealed that the right ventricular pressure curve presented a dip and plateau pattern by cardiac catheterization. Computed tomography of the chest additionally revealed thickened and calcified pericardium in the left ventricle. Abdominal scintigraphy showed tracer accumulation in the transverse colon hepatic flexure 4 h after intravenous administration of technetium-99m-labelled human serum albumin. The patient was diagnosed with a protein-losing gastroenteropathy caused by constrictive pericarditis. He underwent pericardiectomy via left anterior thoracotomy without cardiopulmonary bypass. No complications were present after the surgery, and he was discharged after 46 postoperative days. Following his discharge from the hospital, the pretibial edema disappeared, and serum albumin levels gradually increased and normalized within 3 months after the surgery (TP 7.1 g/dl, Alb 4.2 g/dl).