Vasomotor control of capillary transit time heterogeneity in the canine coronary circulation.

Abstract

INDICATOR-DILUTION studies of the coronary circulation will contain information especially concerning the heterogeneity of capillary transit times, information which potentially can be resolved from outflow curves if both a vascular reference substance, one confined to the coronary circulation, and a diffusible substance, one which leaves the vascular space, have been injected simultaneously. One would expect the heterogeneity to change with changes in the vasomotor tone, and this change, in turn, to affect the manner of presentation 'of diffusible substrates to muscle cells, where they are utilized. It therefore seemed important to us to develop a way of characterizing the heterogeneity of capillary transit times in the myocardium and to use this to define the manner in which the heterogeneity alters in response to changes in vasomotor control. The essence of this methodology is to carry out a set of indicator-dilution experiments, to develop a model of events at the level of the capillary net, and, with this, to try to dissect from the data information concerning the heterogeneity of capillary transit times.

Temporal fluctuations in regional myocardial flows

“…Similarly, the spatial heterogeneity of regional myocardial blood flow has been clearly demonstrated with indicator dilution methods (Bassingthwaighte et al 1972;Rose and Goresky 1976;Roselli and Harris 1979) and with the microsphere technique (Yipintsoi et al 1973;Falsetti et al 1975;Marcus et al 1977;Sestier et al 1978). …”

Heterogeneity of cerebral capillary flow in man and its consequences for estimation of blood-brain barrier permeability.

“…In vasodilated skeletal muscle, E(t) is constant during the upslope of the tracer dilution curve, indicating that the capillaries are homogenous (17). Rose and Goresky (18) observed an increase of E(t) during the upslope of the dilution curve for sucrose in the myocardium (albumin was used as reference). However, in contrast to our observations in the brain, the signs of heterogeneity disappeared in the heart at high flow because the E(t) curves flattened out.…”

The mechanical and metabolic basis of myocardial blood flow heterogeneity

“…The microsphere data describing the flow distributions are used in the analysis of multiple-indicator dilution using models with multiple flow paths in parallel (54). When microsphere data are not available then the effective dispersion method of Haselton et al (47) or the transit time method of Rose and Goresky (83) can be used and are improvements over using a single path model. We feel, however, that both underestimate the real dispersion.…”

“…Guller et al (45) made similar observations but pointed out that the effects of heterogeneity on the estimates of PS c had not been properly ascertained. Goresky et al (43) expressed the same concern and in 1976 Rose and Goresky (83) tried to use an assumed constant PS c in all regions to account for the heterogeneity by using a multicapillary model. They attempted to estimate the heterogeneity itself from the extraction of sucrose during transcapillary passage.…”