What question did this study set out to answer?

To determine how vascular dimensional changes and smooth muscle tone, specifically vasodilation versus vasoconstriction, influence effective blood viscosity across varying flow rates in vivo.

March 1, 1971Acta Physiologica Scandinavica

Effects of Vasoconstriction on Blood Viscosity in Vivo

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Why the study?

Does vasoconstriction affect effective blood viscosity in vivo in the calf muscle vascular bed of cats?

Population

Calf muscle vascular bed of cats

Comparison

Vascular narrowing caused by vessel collapse or… vs Dilated and distended vascular bed

Design

Preclinical

Authors

PBPeter BæckströmVårdcentralen Teleborg BFBjörn FolkowSwedish Defence University EKEd KendrickUniversity of Wisconsin–Madison

Discussion

Member takes

Implication

May limit viscosity's role in low-flow states in vivo; leaves open relevance to human microvascular resistance.

Key Points

To determine how vascular dimensional changes and smooth muscle tone, specifically vasodilation versus vasoconstriction, influence effective blood viscosity across varying flow rates in vivo.
Analyzed pressure-flow curves of blood compared with a Newtonian reference fluid (Dextran-Tyrode) of known viscosity in the calf muscle vascular bed of cats.
Measured effective blood viscosity across wide flow ranges during maximal vasodilation, mechanical vessel collapse, and intense vasoconstriction induced by barium chloride infusion.
In the fully dilated vascular bed, reducing flow from maximal to very low levels increased effective blood viscosity by 200% to 300% from an initial value of approximately 2.35 cP.
During intense barium chloride-induced vasoconstriction with a flow resistance increase exceeding 5000%, effective blood viscosity rose by only about 30% at identical low flow rates.
At equivalent low flow states, effective blood viscosity remained substantially lower in constricted or collapsed vessels than in dilated and distended vessels.

Structured PICO

Does vasoconstriction affect effective blood viscosity in vivo in the calf muscle vascular bed of cats?

Population

Calf muscle vascular bed of cats

Intervention

Vascular narrowing caused by vessel collapse or intense vasoconstriction (barium chloride infusion)

Comparator

Dilated and distended vascular bed (maximal vasodilatation)

Outcome

Effective blood viscosity in vivosurrogate

Effective blood viscosity in vivo remains low and varies little with alterations in vascular tone, indicating it is not a significant determinant of flow even at extremely low flows in constricted beds.

Cite This Study

Bæckström et al. (1971) studied this question.

synapsesocial.com/papers/6a70f1bbac440176ef29a0c3 https://doi.org/10.1111/j.1748-1716.1971.tb04912.x

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Effects of Vasoconstriction on Blood Viscosity in Vivo

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Effects of Vasoconstriction on Blood Viscosity in Vivo

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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Also Consider