Venuloarteriolar signaling helps mediate microvascular function and dysfunction. Mediators produced at venular sites of inflammation appear to constrict arterioles and increase capillary permeability. In contrast, venules beneficially dilate arterioles to enhance capillary flow according to metabolic demand. These mechanisms are altered with cardiovascular risk factors, contributing to microvas...

The effects of beta-adrenergic blockade on cardiac transcapillary exchange were examined at rest and during sympathetic stimulation. Multiple indicator dilution experiments were carried out in closed-chest anesthetized dogs at rest and during carotid occlusion, either under basal conditions or after beta-adrenergic blockade with alprenolol. beta-Adrenergic blockade at rest had no effect on coro...

Blood-tissue transport of 42 K, 8a Rb, and 22 Na was studied in perfused gracilis muscles of dogs to ascertain the influence of capillary wall, interstitial space, and muscle cell membranes on overall transport kinetics. Single-injection and continuous-infusion techniques were used, with T-1824 or 51 Cr-hemoglobin as nondiffusible references. Results were as follows: (1) Extraction (E) of the d...

The passage of a vascular-injected paramagnetic contrast reagent (CR) bolus through a region-of-interest affects tissue (1)H(2)O relaxation and thus MR image intensity. For longitudinal relaxation [R(1) identical with (T(1))(-1)], the CR must have transient molecular interactions with water. Because the CR and water molecules are never uniformly distributed in the histological-scale tissue comp...

A capacitively-coupled contactless conductivity detector (C4D) has been utilised as an on-capillary detector within a capillary ion chromatograph, incorporating a reversed-phase monolithic silica capillary column semi-permanently modified with a suitable ionic surfactant. The monolithic capillary column (150 x 0.1 mm i.d.) was modified using sodium dioctyl sulfosuccinate (DOSS), an anionic surf...

OBJECTIVE To review the status of haemoglobin-oxygen affinity in critical illness and investigate the potential to improve gas exchange, tissue oxygenation and outcome by manipulations of the oxyhaemoglobin dissociation curve. DATA SOURCES Articles and published peer-review abstracts. SUMMARY OF REVIEW The P50 of a species is determined by natural selection according to animal size, tissue ...

Needless to say, the different vascular circuits and their consecutive sections are designed to meet the particular demands of their tissues, both as to the range of blood supply and as to how this supply is distributed and put into efficient exchange within the tissue. Not only the dimensions of the resistance vessels but also the capillary permeability and surface area are therefore closely t...

Responses to exchange transfusion using red blood cells (RBCs) with normal and reduced flexibility were studied in the hamster window chamber model during acute moderate isovolemic hemodilution to determine the role of RBC membrane stiffness in microvascular perfusion and tissue oxygenation. Erythrocyte stiffness was increased by 30-min incubation in 0.02% glutaraldehyde solution, and unreacted...