Retrograde secretion of bile salts and other potentially toxic cholephiles As an adaptive mechanism during cholestasis, basolateral conjugate transporters such as ABCC3/ MRP3 are upregulated and cholephiles such as bilirubin glucuronides, which are not adequately secreted into bile, can leave the liver cell via the basolateral route. In contrast to the postulated increase in retrograde secretion [228] , UDCA diminishes basolateral efflux due to the effective stimulation of orthograde secretion of potentially toxic compounds into the bile.