Ion transport and structure of urinary bladder epithelium of Amphiuma

The urinary bladder of Amphiuma exhibits stable transport properties and an electrical potential difference in vitro. The lumen is significantly negative to the serosa and under short-circuited conditions flux rations for Na and Cl of 5.92 +/- 0.42 and 1.81 +/- 0.20, respectively, were observed. The close agreement between the short-circuit current and net Na flux suggests that most, if not all, of the current is carried by Na. Both ouabain and amiloride decreased the short-circuit current and the mucosal-to-serosal (M leads to S) flux of Na. Furosemide caused a transient increase in the M leads to S flux of Na and Cl but ADH was without effect. In bladders that had high transmural resistance, a net movement of K in the M leads to S direction under short-circuited conditions with flux ratios of up to 2 could be observed. The epithelium of the Amphiuma bladder consists of three cell types: granular cells, basal cells, and mitochondria-rich cells. No goblet cells are present. The mitochondria-rich cells comprise less than 5% of the population of the surface epithelium in Amphiuma in contrast to other amphibian bladders, where it accounts for up to 25% of the population.     

The effects of pentylenetetrazol on molluscan neurons. II. Voltage clamp studies

The effects of pentylenetetrazol (PTZ) upon the steady and transient outward ionic currents during PTZ-induced prolonged depolarizations were investigated using voltage clamp techniques. PTZ causes a 5-35% reduction in gL and a 40-60% reduction in steady-state gK. There is also a marked reduction in the activation of gA of Connor and Stevens6 at all clamp potentials; a shortening of the time constant for the inactivation of gA; and a 10-15 mV shift in the depolarizing direction of the curve relating the steady-state inactivation of gA to membrane potential. The equilibrium potentials for both gA and gK are depolarized by 20 mV in PTZ solution. Equation and voltage clamp data for normal repetitive firing were integrated with the normal and PTZ-alered data. Solution to these equations demonstrated: (1) normal repetitive firing in response to a constant current stimulus; and (2) PTZ-altered repetitive firing that was in the direction of, and for the most part, similar to the observed behavior.     

Renal toxicity. Tobramycin and gentamicin

To see if urinary 2-methyl-4-chlorophenoxyacetic acid (MCPA) excretion could be used to estimate MCPA exposure, four healthy males ingested 5 mg MCPA. The MCPA in the urine was extracted and anlyzed by high pressure liquid chromatography. About 50% of the ingested dose was detected in the urine within 48 h. On the fifth day after intake the MCPA concentration in the urine was below the level of detection, 0.2 microgram/ml. The MCPA did not increase those serum enzymes indicating liver cell damage (S-alanine-aminotransferase, S-alkaline-phosphate). Some creatine kinase (CK) and S-aspartate-aminotransferase (ASAT) values were pathological, but, as all CK values were normal in two persons and all ASAT values were normal in three persons, it not likely that MCPA had a toxic effect on muscle cells. MCPA in urine seems to be a useful indicator of MCPA intake in humans. All the urine passed within 48 h of MCPA exposure must be collected.     

Double bond position affects metabolism of cis-Octadecenoates

The metabolic fate of cis-positional isomers of octadecenoates has been compared to that of naturally occurring oleic acid (cis-delta9). Radioactive mixtures of tritium-labeled positional octadecenoate isomer and oleic acid-10(-14)C were administered to laying hens, and their eggs were analyzed for the isotopic ratios (3H/14C) incorporated into total egg lipid, triglycerides, and phospholipids. Variations in the isotopic ratios indicated the comparative metabolic utilization of cis-positional isomers delta8 through delta12. Incorporation into egg lipid fractions is as follows: triglycerides: delta9 greater than delta8, delta9 greater than delta10, delta9 greater than delta11, delta9 greater than 12; phospholipid: delta9 greater than delta8, delta9 greater than delta10, delta9 less than delta11, delta9 less than delta12.     

Analysis of baby hamster kidney cells persistently infected with lymphocytic choriomeningitis virus

The possibility has been demonstrated of using the method of aggregate-haemagglutination for the detection of B. cereus exo-enterotoxin in both food products and culture media. It has been established that 0.004 mug/ml of enterotoxin can be detected by this method. The applied antisera to B. cereus enterotoxin did not yield cross reactions with enterotoxins produced by E. coli, Cl. perfringens, St. aureus, V. cholerae or Sh. dysenteriae.