We examined the biological and histologic characteristics of a new experimental model of acute necrotizing pancreatitis induced by excessive doses of arginine in rats. Rats were given a single intraperitoneal injection of 500 mg/100 g body weight of L-arginine. At 12-24 hr after the arginine injection, serum levels of amylase, lipase, and anionic trypsin(ogen) reached respective peak values 2, 5, and 20 times those of control rats without arginine and returned to control levels after 24-48 hr. The contents of pancreatic protein, DNA, and digestive enzymes were markedly reduced after the arginine injection and reached their nadirs at 72 hr. After 14 days these levels were almost normal. Histologic examination revealed a number of small vesicles within acinar cells at 6 hr, which were identified as markedly swollen mitochondria by the electron microscope. Other intracellular organelles and nuclei also showed degenerative changes. At 12 hr interstitial edema appeared, and acinar cell necrosis was seen after 24 hr. The extent and severity of necrotic changes of pancreatic exocrine tissue with inflammatory cell infiltration were maximal at 72 hr. At seven days, pancreatic acinar cells began to regenerate, and pancreatic architecture appeared almost normal after 14 days. The present study has demonstrated that the administration of excessive doses of arginine induces a new, noninvasive experimental model of acute necrotizing pancreatitis.

The adsorbed films of alkylammonium halides, 1C n TAX and 2C n DAX with alkyl chain lengths of n = 1, 6, 8, 10, 12, 14, 16, and 18, on cleaved mica surfaces was analyzed by atomic force microscopy for their two-dimensional arrangement and molecular area. The stable hydrophobic surface was obtained by cleaving mica in an adsorption bath and stands for prolonged adsorption time of 72 h at 5 °C. The adsorbed molecules are stable and do not desorb easily when put in distilled water. The occupied area of double-chained alkylammonium bromides, 2C n DAB, on a mica surface was found to range from 0.45 to 0.47 nm2, which is equivalent to the density of a potassium ion (1/0.47 nm-2), while the single-chained alkylammonium halides, 1C n TAX, showed the area ranging from 0.23 to 0.24 nm2 per molecule, which is half the density of a potassium ion (1/0.47 nm-2) on a mica surface. The symmetry of the two-dimensional arrangement of adsorbed molecules agreed with the lattice structure of a cleaved mica surface despite the numbers and the lengths of alkyl chains.

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