Effects of charge on membrane processing in the proximal nephron.

To examine the effects of molecular charge on membrane processing in renal tubular cells, the distribution of cationic and anionic ferritin was characterized in microperfused proximal nephron segments. During the first 7 min of proximal tubule perfusion, cationic ferritin was observed 1) bound to the brush-border membrane, 2) in apically positioned vesicles and vacuoles, 3) in lysosomes, 4) in vesicles adjacent to the basolateral plasmalemma, and 5) bound to the basolateral plasmalemma. Compared with anionic ferritin, the distribution of cationic ferritin was characterized by 1) a smaller relative grain density for lysosomes, 2) an accumulation of granules in an enlarged pool of apical cytoplasmic vesicles and vacuoles, and 3) a greater number of granules reaching the basolateral plasmalemma.

Carrier-mediated transport of pyroglutamyl-histidine in renal brush border membrane vesicles.

These studies were performed to determine if a transmembrane carrier for pyroglutamyl-histidine (pGlu-His) is present in the luminal membrane of renal proximal tubular cells. Previous studies have suggested the intact transepithelial transport of pGlu-His, a dipeptide formed by the hydrolysis of luteinizing hormone-releasing hormone by enzymes associated with the brush border in the proximal nephron. With the use of a renal brush border membrane vesicle preparation, pGlu-His showed H+-stimulated, Na-independent, saturable transport into an osmotically active space.

Bacterial peptidoglycans as modulators of sleep. II. Effects of muramyl peptides on the structure of rabbit sleep.

Sleep-promoting substances derived from human urine and rabbit brain were identified as muramyl peptides (MPs). We report in the accompanying paper that in the molecular structure of MPs, the 1,6-anhydro muramic acid moiety of MPs is important for enhancement of slow-wave sleep (SWS) in rabbits. Here, we document more extensively the effects of one MP: 1,6-anhydro-muramyl-alanyl-glutamyl-diaminopimelyl-alanine (AMTP for anhydro-muramyl tetrapeptide) on sleep structure of rabbits.

Bacterial peptidoglycans as modulators of sleep. I. Anhydro forms of muramyl peptides enhance somnogenic potency.

Chemically defined muramyl peptides (MPs), derived primarily from enzymatic digests of Neisseria gonorrhoeae peptidoglycan, were used to define the structural determinants of MP-mediated somnogenic activity. One of these, i.e.

Interferon alpha-2 enhances slow-wave sleep in rabbits.

Interferon alpha-2 (IFN) is a leukocyte product with several biological properties including antiviral activity, pyrogenicity and enhancement of immune functions. We report here that an additional facet of IFN activity is its ability to enhance slow-wave sleep (SWS) without greatly altering other aspects of sleep. Intravenous or cerebral intraventricular injections of human IFN into rabbits induced enhancement of SWS, electroencephalographic slow-wave (0.