Differential effect of hyperthermia on nerves and smooth muscle of the mouse ileum.

摘要

BACKGROUND AND OBJECTIVES: Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) gained wide acceptance as the treatment of choice for selected patients with peritoneal surface malignancies. Patients tend to suffer from prolonged ileus following CRS + HIPEC, complicating their recovery. We studied the effects of hyperthermia on the intestine to gain insight into mechanisms of ileus post-HIPEC. METHODS: Segments of mouse ileum were incubated at 36 degrees C. Electrical field stimulation (EFS) was applied, stimulating nerves, and the resultant muscle contraction was measured. The response was measured at varying temperatures (38-43 degrees C) at exposure times of up to 120 min. We also stimulated the tissues with 10(-6) M carbachol, a muscarinic receptor agonist, which acts directly on smooth muscle. RESULTS: Response to EFS decreased at high temperatures, especially above 41 degrees C. This effect was irreversible for 120 min after decreasing temperature. When stimulating with carbachol, both transient and plateau responses decreased at 43 degrees C (plateau more than transient) but the effect reversed on returning to 36 degrees C. CONCLUSION: The irreversible decline in responses to nerve stimulation when exposed to high temperatures was not seen with direct muscle stimulation. This indicates that smooth muscle is resilient and that the main effect of hyperthermia is on nerves. These results have significance for HIPEC.