Spatial heterogeneity in striated muscle arteriolar tone, cell flow, and capillarity.
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.
Sweeney
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Department of Biophysics, University of Rochester, School of Medicine and Dentistry, New York 14642.
Sarelius
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IH
D000818:Animals; D001158:Arteries / Q000502:physiology*; D001160:Arterioles / Q000166:cytology / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002197:Capillary Action; D002465:Cell Movement / Q000502:physiology; D006224:Cricetinae; D004906:Erythrocyte Count; D004912:Erythrocytes / Q000166:cytology / Q000502:physiology; D005434:Flow Cytometry; D008297:Male; D008647:Mesocricetus; D008833:Microcirculation; D009132:Muscles / Q000098:blood supply* / Q000166:cytology / Q000502:physiology; D012039:Regional Blood Flow