Tissue water volume

We are going to use as an example a five-organ compartment model for the metabolism of ethanol in humans. We will apply the CRE algorithm to the tissue water volume in each organ. The TWVs are lumped according to their perfusion rates and... 

We will now discuss the balance equation on the tissue water volume of each of the organs/compartments. 

Ethanol is absorbed virtually instantaneously in the duodenum at the entrance of the G.l. tract. In addition, the blood flow to the G.L compartmcni from the central com-paitment to the G.l. tract is two-thirds of the total blood flow with the other third by-passing the G.l. tract to the liver, as shown in Figure E7-7.1. A mole mass balance on ethanol in the G.l. tract tissue water volume (TWV) V, gives... 

Fig. 6. Spatial distribution of net osmoticum deposition rate per mm of tissue water in the apical 10 mm of maize primary roots growing at various vemiculite water contents (see Fig. 3). The data were obtained by dividing rates per mm length (Fig. 5) by the volume of water in each segment. The inset shows root diameter as a function of distance from the apex in the different treatments. Points are means s.d. ( = 5-6). Modified from Sharp et al. (1988, 1989).

Mannitol Physical osmotic effect on tissue water distribution because it is retained in the vascular compartment Marked increase in urine flow, reduced brain volume, decreased intraocular pressure, initial hyponatremia, then hypernatremia Renal failure due to increased solute load (rhabdomyolysis, chemotherapy), increased intracranial pressure, glaucoma IV administration Toxicity Nausea, vomiting, headache... 

A two mL capacity polypropylene container with sealable screw-top lid and V shaped bottom. Ideal for storing dried organisms (e.g., amphipods) and water samples and good for digesting small tissue samples because small acid volumes remain in contact with tissue samples. Volume 1(12). 

Currently, there is no doubt that the most widely used method for extraction of tissue lipids is that of Bligh and Dyer (1959). Basically, this is a modification of the Folch method and employs a careful calculation of the amount of sample (tissue) water such that the overall mixture will have a final composition of chloroform-methanol-water of 1 2 0.8 (v/v). Thus, a singlephase extract can be obtained and extraction completed very rapidly, even within minutes. Recovery of the lipid in a chloroform-rich phase can be achieved by addition of equal volumes of chloroform (under certain conditions) and water to produce a two-phase system. The lower (CHC13) phase is subsequently washed with a methanol-water (1 0.9, v/v) mixture to allow removal of a substantial amount of the nonlipid contaminant with little or no problems with interfacial fluff formation or emulsions. However, even though this is a highly efficient method, it is still advisable that one take steps... 

It is distributed to the tissues having volume of distribution v/ more than the total body water. The drug gets metabolized by the hepatie mierosomal system to the eorresponding alkylating metabolites, which in turn eventually are duly converted to phosphoramide mustard and acrolein (an aldehyde). However, the relatively high doses readily induce the metabolism of cyclophosphamide. The plasma half-life ranges between 4 to 6 hours. 

Thus, the volume of distribution of the central compartment in which peptides and proteins initially distribute after intravenous administration is typically 3 to 8 L, approximately equal to slightly higher than the plasma volume [19] (approximate body water volumes for a 70-kg person interstitial 12 L, intracellular 27 L, intravascular 3 L) [34]. The total volume of distribution (V ) is frequently 14 to 20 L, not more than twice the initial volume of distribution (Vc) [13, 28]. This distribution pattern has, for example, been described for the somatostatin analog octreotid (Vc 5.2-10.2 L, VIIIa inhibitor eptifibatide (Vc9.2 L) [35-37].Active tissue uptake and binding to intra- and extravascular proteins, however, can substantially increase the volume of distribution of peptide and protein drugs, as, for example, observed with atrial natriuretic peptide (ANP) [38]. 

The volume of distribution of aminoglycosides is increased in young calves relative to adults, as a consequence of high extracellular water volume relative to body weight, because volume of distribution is proportional to plasma volume. Volumes of distribution are lower in obese animals, as aminoglycosides penetrate very poorly into adipose tissue. Overall, volume of distribution (Vrf,area) is of the order of 0.15-0.45 1/kg, and the clinically relevant terminal half-life (P phase) is 1.0-2.0 h. 

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