Plasma and gastric mucosal 5-hydroxytryptamine concentrations following cold water intake in patients with diarrhea-predominant irritable bowel syndrome.

BACKGROUND AND AIM: The purpose of the present paper was to investigate the effects of cold water intake on 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindole acetic acid (5-HIAA) in diarrhea-predominant irritable bowel syndrome (d-IBS) patients, and to observe the relationship between 5-HT and symptomatology. METHODS: The plasma 5-HT/5-HIAA concentrations at 0, 30 min, 60 min, 90 min, 120 min, 150 min and 180 min following cold or warm water intake were investigated in 32 female subjects with d-IBS and 21 healthy female subjects. Gastric mucosal 5-HT under fasting conditions and following water intake were further investigated in 15 d-IBS patients and nine healthy subjects. Symptomatology was assessed throughout the study. RESULTS: The plasma 5-HT concentrations in IBS patients were significantly higher than those of controls at 30 min (P = 0.022), 60 min (P < 0.001), 90 min (P < 0.001), 120 min (P < 0.001) and 150 min (P = 0.001) after cold water intake. The peak plasma 5-HT/5-HIAA and area under the curve for 5-HT/5-HIAA were also higher in d-IBS patients (P < 0.001). Gastric mucosal 5-HT in d-IBS patients and controls did not show any significant differences both under fasting condition (P = 0.596) and after cold water intake (P = 0.426). Last, the d-IBS patients with symptoms had higher 5-HT concentration (P < 0.001) and there was a positive correlation (r = 0.714, P = 0.001)between the symptomatology and plasma 5-HT level. CONCLUSIONS: These data suggest that symptomatology following cold water intake may be associated with increased plasma 5-HT concentrations in female subjects with d-IBS.

Alterations in cerebral potentials evoked by rectal distention and drinking ice water in patients with irritable bowel syndrome.

AIM: Visceral hypersensitivity has been found to be present in irritable bowel syndrome (IBS). The current study sought to study visceral afferent hypersensitivity in IBS patients and obtain further objective evidence of alterations in intestinal afferent pathways in IBS patients by cerebral evoked potentials (CEP). METHOD: We studied 30 female IBS patients and 12 female healthy subjects. Rectal perception thresholds to balloon distention were measured and CEP was recorded in response to rhythmic rectal distention (two distention series, each of 100 repetitions at a frequency of 1 Hz) at the volume of perception thresholds. All subjects were then asked to drink 220 mL 4 degrees C ice water and the above steps were repeated 20 min later. RESULTS: Rectal distention led to recognizable and reproducible CEP. Compared to healthy subjects, IBS patients demonstrated significantly shorter N1, P1 and N2 latencies (P < 0.05). After drinking ice water, IBS patients exhibited further shortened N1, P1 and N2 latencies (P < 0.05), but drinking did not alter the latencies of healthy controls and the amplitudes of both IBS patients and healthy controls. CONCLUSION: The shorter latency of cerebral potentials evoked by rectal distention and ice water stimulation in IBS patients provided further objective evidence for defective visceral afferent transmission in IBS patients.

Visceral hypersensitivity following cold water intake in subjects with irritable bowel syndrome.

BACKGROUND: Visceral hypersensitivity has been shown to be present in irritable bowel syndrome (IBS). This study sought to investigate rectal sensitivity and abdominal symptoms in IBS patients before and after 220 ml cold water intake. METHODS: A total of 60 IBS patients and 18 healthy controls participated in this study. Both the perception thresholds and defecation thresholds to rectal balloon distension were measured. Then, all subjects were asked to drink 220 ml 37 degrees C warm water or 4 degrees C cold water, and these steps were repeated 20 min later. Symptoms including abdominal pain/discomfort, bloating, and diarrhea were recorded during the study. RESULTS: Compared with the controls, the thresholds of initial sensation to rectal balloon distention in IBS patients were significantly lower while the defecation thresholds were higher in constipation-predominant IBS patients. After drinking cold water, the perception thresholds in IBS patients and the defecation thresholds in diarrhea-predominant IBS patients were further decreased. However, warm water intake did not change the perception thresholds significantly in either IBS patients or controls. A negative linear correlation was found between the symptoms and the visceral perception thresholds in diarrhea-predominant IBS patients who showed significant symptoms after cold water intake. CONCLUSION: The results indicated that cold water intake leads to lowered visceral perception thresholds in IBS patients that were inversely relevant to the abdominal symptoms in symptomatic diarrhea-predominant IBS patients. The alteration of rectal sensitivity and abdominal symptoms following cold water stimulation provided further objective evidence for visceral hypersensitivity in IBS patients.