Gallbladder mucosal protein secretion during development of experimental cholecystitis

The development of experimental cholecystitis produced by lysophosphatidylcholine is associated with reversal of the normal absorptive characteristics of gallbladder mucosa, resulting in the intraluminal accumulation of water, glycoprotein, and protein. The purpose of the present study was to attempt to ascertain if the protein leaks into the lumen because of the cytolytic properties of lysophosphatidylcholine or if it is due to an active secretory process and to characterize the protein produced. Experiments were performed on anesthetized cats undergoing gallbladder perfusion with and without lysophosphatidylcholine. The amount of protein in the perfusate was measured and albumin clearance from blood to gallbladder lumen was calculated with and without the administration of vesicular transport inhibitors. In separate experiments, control and lysophosphatidylcholine (LPC) produced gallbladder perfusates were collected and the protein subjected to SDS-PAGE to ascertain the nature of the protein secreted. Inhibitors of both microtubular and microfilament activity decreased the protein accumulation and clearance produced by lysophosphatidylcholine. Gallbladder white blood cell accumulation and inflammation as evaluated by beta-glucuronidase and prostaglandin E levels were not significantly altered by cytochalasin or colchicine administration. Lysophosphatidylcholine also produced significant increases in perfusate LDH levels. The protein produced was primarily a 66-kDa protein. Transfer of the protein to a nitrocellulose membrane and immunoblotting with anti-albumin antibody demonstrated that the protein was albumin. The results suggest that during the development of cholecystitis, lysophosphatidylcholine produces albumin accumulation in the gallbladder primarily by inducing an active secretory process resulting in gallbladder distension.