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Spatial heterogeneity in striated muscle arteriolar tone, cell flow, and capillarity
1Department of Biophysics, University of Rochester, School of Medicine and Dentistry, New York 14642.
Insights
Microvascular function varies significantly across different tissue sites in hamster cremaster muscle. Terminal arterioles and capillary network controllers show distinct spatial differences in blood flow and vessel tone.
Area of Science:
- Physiology
- Microcirculation Research
- Vascular Biology
Background:
- Microvascular networks exhibit complex structures and functions.
- Understanding spatial variations in microvascular function is crucial for comprehending tissue perfusion and oxygen delivery.
Purpose of the Study:
- To investigate spatial heterogeneity in microvascular function within the hamster cremaster muscle.
- To compare microvascular parameters at two distinct tissue sites.
Main Methods:
- Analysis of terminal arterioles and capillary network controllers (CNCs) in hamster cremaster muscle.
- Measurement of vessel diameter, cell flow, and capillary exchange indices under resting and hyperemic conditions.
Main Results:
- Terminal arterioles at site I showed greater resting constriction and lower flow compared to site II.
- Capillary network controllers exhibited higher resting flow at site II than at site I.
- Capillary segment length and erythrocyte content were significantly higher at site I during hyperemia.
Conclusions:
- Significant spatial variations in microvascular function, including vessel tone and cell flow, exist within the hamster cremaster muscle.
- These differences impact capillary exchange and tissue perfusion.
- The study highlights the importance of considering spatial heterogeneity in microvascular research.
Abstract:
Spatial variations in microvascular function are described at two tissue sites in hamster cremaster muscle (pentobarbital sodium, 70 mg/kg ip). Arterioles observed include terminal arterioles and their feeding vessels, termed capillary network controllers (CNC). Although terminal arterioles at both sites had similar maximum diameters and cell flows, those at site I were significantly more constricted at rest (2.7 +/- 0.3 vs. 5.1 +/- 0.3 microns at site II) and showed lower resting flows (19.0 +/- 5.5 vs. 174 +/- 34 cells/s at site II). There were no spatial differences in CNC maximal parameters or CNC resting tone, yet CNC resting flow at site II (798 +/- 118 cells/s) significantly exceeded the value at site I (460 +/- 85 cells/s). At rest, median capillary cell flow at site I (3.3 cells/s) was half that at site II (6.3 cells/s). During hyperemia, perfused capillary segment length per unit volume was 84% greater at site I and estimated tissue erythrocyte content nearly double that at site II. Thus significant spatial differences in microvascular function exist in cell flow and vessel tone among terminal arterioles, in cell flow among CNC, and in capillarity and indices of capillary exchange.