Isolated hepatocytes prepared from sheep fed a basal diet (bromegrass hay-corn, 50:50 wt/ wt, as-fed basis) with or without urea were used to determine the effects of added ammonia (as NH4Cl) and propionate on the partitioning of C from 1.25 mM L-[1-14C]alanine between oxidation and gluconeogenesis, and the flux of 15N from 1.25 mM L-[15N]alanine to [14N15N]urea and [15N15N]urea. Hepatocyte sus...

The rate of unidirectional [14C]urea efflux from human red cells was determined in the self-exchange and net efflux modes with the continuous flow tube method. Self-exchange flux was saturable and followed simple Michaelis-Menten kinetics. At 38 degrees C the maximal self-exchange flux was 1.3 X 10(-7) mol cm-2 s-1, and the urea concentration for half-maximal flux, K1/2, was 396 mM. At 25 degre...

The role of urea as a balancing osmolyte in osmotic adaptation is well known, but this 'waste product' also has myriad other functions in diverse taxa. We report that urea plays an important, previously undocumented role in freezing tolerance of the wood frog (Rana sylvatica), a northern woodland species that hibernates terrestrially in sites where dehydration and freezing may occur. Wood frogs...

in order to evaluate the effects of ethephon and nitrogen fertilizer on sweet sorghum cv. sofra, an experiment was conducted as split plot on a randomized complete block design with three replications at agricultural research station of isfahan university (isfahan, iran). experiment was conducted with four nitrogen levels (0, 100, 200 and 300 kg urea ha-1 from urea with 0, 46, 92 and 138 kg nit...