The effect of polycythemia on blood flow in working and non‐working skeletal muscle

Abstract

The effect of acutely induced polycythemia on blood flow and viscosity in the vasodilated vascular bed of working and non-working skeletal muscle was studied. In 12 mongrel dogs anesthetized with thiopental sodium the calf muscle of one hind limb was isolated. Vasodilation was induced either by sciatic stimulation setting the muscle at maximal work or by i.a. infusion of papaverine. Blood flow was measured at different perfusion pressure before and after infusion of 300 ml packed homologous red cells. Blood viscosity in vitro was determined in a coneplate viscometer. Apparent viscosity in vivo was analyzed by comparing pressure-flow relationships for blood and a reference solution. Polycythemia decreased blood flow by 35% in the non-working muscle but less than 10% in the working muscle at comparable perfusion pressures. Blood viscosity in vitro increased by 35% at low shear rates. Apparent viscosity in vivo increased by 35% in the non-working muscle but less than 10% in the working muscle. The flow impairment induced by polycythemia was far more pronounced in the non-working skeletal muscle indicating a flow facilitation by the rhythmic muscle contractions. Erythrocyte flow in fact increased in the working muscle after induced polycythemia while decreased in the non-working muscle.

Blood flow and in vivo apparent viscosity in working and non-working skeletal muscle of the dog after high and low molecular weight dextran.

“…A similar flow-preserving effect has been shown to exist after acutely induced polycythemia (Gustafsson et al, 1980). A high hematocrit was found to be more deleterious to the oxygen availability in the resting muscle than in the exercising muscle.…”

“…1), the surgical preparation being similar to the one described in a previous study (Gustafsson et al, 1980). The thigh muscles were divided above the knee joint, as were all vessels except the popliteal artery and vein.…”

“…In a previous study we found that rhythmic muscle contractions facilitated flow at increased hematocrits (Gustafsson et al, 1980). The purpose of the present investigation was to study the influence of rhythmic muscle contractions on in vivo apparent viscosity and flow during a state of red cell aggregation and increased plasma viscosity induced by HMWD and packed red cells and, furthermore, to evaluate the effect of subsequent hemodilution with LMWD.…”

Regulation of oxygen delivery during induced polycythemia in exercising dogs

“…Whereas viscosity rises in a curvilinear fashion with increasing polycythemia, cardiac output falls in a much more linear fashion (3,22). Similar falls in cardiac output occur both at rest and with exercise during polycythemia even though viscosity changes are minimized in exercising muscle beds (10,22). Finally, several studies have shown that exercise capacity and maximal oxygen uptake may not fall with polycythemia as had been previously described (12,22).…”

Effects of Hemodilution on Skeletal Muscle Blood Flow and Blood Viscosity in vivo after Splanchnic Stasis

“…An increase in hematocrit from 46-61 % should not per se decrease flow more than about 40-50% as evident from other studies concern ing relationships between hematocrit and pressure-flow curves in skeletal muscle prep arations [4,11,15,17]. It therefore seems that the hypotensive state contributes to the pronounced changes in vivo, possibly by plugging of the microvascular bed.…”