Kallikrein was localized in goblet (or mucous) cells of rat colon and in rat and cat small intestine and stomach by two immunocytochemical techniques. A kallikrein-like enzyme was also localized by enzyme histochemistry in mast cells of colon, intestine, and stomach of the cat, where they appeared to be associated with blood vessels in the lamina propria. The mast cell enzyme, however, was not detected by immunocytochemistry using antibodies to kallikrein. Modification in the enzyme histochemical procedure (pH, fixation) yielded positive results for a kallikrein-like protease in goblet cells of the intestine and colon. The possible physiological and pathological significance of kallikrein-like enzyme in the gastrointestinal tract and elsewhere is discussed.

We studied the penetration of fluorescein isothiocyanate (FITC) T-40 dextran into the paracellular spaces in the tracheal mucosa and its appearance in the blood plasma of guinea pigs exposed to cigarette smoke or (controls) breathing room air. Under general anesthesia, the dextran solution was instilled onto the tracheal surface via a tracheotomy tube, arterial blood was sampled serially for 40 min, and then the trachea was fixed by perfusion or immersion. Examination of the tracheal mucosa with light microscopy, with and without epifluorescence, and transmission electron microscopy, revealed dextran in the paracellular spaces in mucosa from experimental animals but not controls. In all control animals, the levels of the dextran in plasma was below the sensitivity of the assay. By contrast, dextran levels in the plasma from the experimental animals fell within the sensitivity range of the assay and increased in blood at a rate of 0.00125 +/- 0.00023 (SE) expressed as a percentage of the instilled dose/min. We conclude that FITC T-40 dextran provides a reliable, fairly simple, fast method for assessing major, but not subtle, changes in paracellular permeability of the tracheal mucosa.

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The effect of cystic fibrosis plasma on the net fluxes of 45Ca t and :"SO2 across the guinea-pig stomach and small intestine was investigated, using an automatic short-circuit current apparatus."' A significant increase in net fluxes across the stomach and small intestine for 4 Ca t in the presence of cystic fibrosis plasma compared with non-cystic fibrosis plasma was observed. There was an increase in net flux for ' SO,2across the stomach in the presence of cystic fibrosis plasma when compared with non-cystic fibrosis plasma. However, there was a more highly significant increase in net fluxes for 3"SO42across the small intestine in the presence of cystic fibrosis plasma when compared with non-cystic fibrosis plasma. The amount of 45Ca2+ activity retained by the stomach and small intestine is more highly significant in the presence of cystic fibrosis plasma than in the presence of non-cystic fibrosis plasma. The retention of 35S042activity by the stomach and small intestine in the presence of cystic fibrosis plasma when compared with non-cystic fibrosis plasma was also highly significant. These findings indicate that cystic fibrosis plasma increases the net fluxes and raises retention of 't'Ca2t and SO,2 in guinea-pig stomach and small intestine. College, Campden Hill Road, London W8 7AH.

The ultrastructure of skeletal muscle and activity of some enzymes of energy metabolism were studied to assess the effect of a deficiency of dietary energy and subsequent nutritional rehabilitation in 24 young, growing, healthy rhesus monkeys. Electron microscopy of muscles on energy-deficient animals showed thinning of myofibrils with widening of interfibrillar space and enlargement and accumulation of mitochondria at subsarcolemmal level. There was an apparent significant reduction in the fiber size. Muscle samples from each animal were analyzed for enzymes representative of glycolysis (phosphofructokinase [PFK] and lactate dehydrogenase [LDH], citric-acid cycle (isocitric dehydrogenase [ICDH] and citrate synthase [CS] and regeneration of ATP (creatine kinase [CK]. PFK and LDH activities were significantly augmented in energy-deficient animals. The increase in LDH activity resulted from a large increase in MU (skeletal muscle) LDH subunit. The activities of CS and ICDH were reduced. No alteration of CK in muscle and serum was observed. The morphological structure and enzyme activities returned to normal after nutritional rehabilitation.