Dual effect of [ d-Pen 2, d-Pen 5]enkephalin on ion transport in guinea pig colon

Abstract

Effects of the δ-opioid receptor ligand, [ d-Pen 2, d-Pen 5]enkephalin (DPDPE) on basal and endothelin-1-induced ion secretion in guinea pig colon were investigated. Muscle-stripped segments of guinea pig colon were mounted in Ussing flux chambers and changes in the short-circuit current ( I sc) were monitored continuously. DPDPE significantly reduced baseline I sc at a low dose, 1 nM; however DPDPE increased I sc at 10 and 100 μM. Endothelin-1 stimulated ion secretion that was unaltered in tissues pretreated with DPDPE. In guinea pig colon, δ-opioid receptor activation evoked both a proabsorptive and prosecretory response.