The doses of antibodies were chosen so that concentrations in vivo should by far exceed on a molar basis the expected concentrations of endogenous plasma ADM.
Tissue concentrations of endogenous chemicals and nutrients are in large part regulated by membrane transporters through their substrate specificity and differential tissue distributions.
In the blood-brain barrier (BBB), P-gp are responsible for pumping toxic compounds out of the brain, resulting in low concentrations of endogenous and exogenous compounds in the brain.
The relative increase of vasoconstrictor sensitivity in the splanchnic circulation during early pregnancy may prevent hypotensive dysregulation, while concentrations of endogenous vasodilators rise and the vascular filling state normalizes only gradually.
The concentrations of endogenous ACh were calculated based on the peak area ratio of the analyte to the IS using a regression equation for the corresponding surrogate standard ACh-d44).
Nonetheless, it is not only the optical or nuclear methods that are able to provide functional information; fMRI and MRS have evolved to become powerful tools for detecting changes in blood flow, tissue oxygenation or concentrations of endogenous molecules such as lactate, choline or N-acetyl-aspartate.
While these lines of research suggest a role for the endocannabinoid system in female sexual functioning, no studies investigating the relationship between concentrations of endogenous cannabinoids (i.e., arachidonoylethanolamide [AEA] and 2-arachidonoylglycerol [2-AG]) and sexual functioning have been conducted in any species.
This study was designed to investigate the effect of diabetic duration on serum concentrations of endogenous inhibitor of nitric oxide synthase NG, NG-asymmetric dimethylarginine (ADMA) in patients and rats with diabetes, and to determine whether elevated endogenous ADMA is implicated in endothelial dysfunction or macroangiopathy in diabetes.
This correlation was not broken even in cases in which the tumor cells expressed significant concentrations of endogenous semaphorins.
Finally, the difficulty of monitoring the concentrations of endogenous ligands in the tissue of interest has complicated the interpretation of the studies of GPCR activation in vivo.
This minimal/absent use of the PXR feed-back loop by endogenous agonists may be logical, as concentrations of endogenous ligands high enough to significantly activate PXR would only occur in pathophysiological conditions when it would be important to return to homeostasis as soon as possible and not limit the rate of CYP3A1-mediated degradation.
