Ionic flux and mucosal ultrastructure in the rat bile-pancreatic duct. Effect of bile salt perfusion on duct integrity.

The property of the pancreatic ductal system that restricts free ionic diffusion has been termed the "pancreatic duct mucosal barrier," damage to which may be important in the pathogenesis of acute gallstone pancreatitis. The bile-pancreatic duct of the rat (BPD) was perfused in situ with a standard ionic solution. The normal duct was permeable to both chloride and bicarbonate ions, and flux (JCl-, JHCO3-) appeared to occur by passive ionic diffusion. Measurement of absolute ionic flux and transductal potential difference (PD) gave control values of JCl-, +0.92 +/- 0.15 mumol/cm/hr; JHCO3-, -1.71 +/- 0.12 mumol/cm/hr; PD -2.3 +/- 0.20 mV. The preparation was stable over the experimental period, and the results obtained were reproducible between animals. Glycodeoxycholate compromised the integrity of the BPD with an increase in ionic flux and a reduction in PD with corresponding alterations in mucosal ultrastructure. Increasing concentrations of bile salt produced more severe damage to the BPD. The BPD of the rat is therefore analogous to the pancreatic duct of the cat in possessing a mucosal barrier, and the barrier is damaged by bile salts. This preparation may be useful for studying pancreatic duct integrity, a concept of importance in the pathogenesis of acute gallstone pancreatitis.