Method for continuous recording of hydrostatic exchange vessel pressure in cat skeletal muscle

Abstract

A venous microcannulation technique applied to the cat gastrocnemius muscle was developed which, based on morphological and functional demonstrations of anastomotic connections between two supplying segmental vascular circuits at the level of capillaries and/or post-capillary venules, seems to permit continuous recordings of hydrostatic pressure (denoted Pcvenule) transmitted from such anastomoses, that is, from a site close to the main fluid exchange vessels. For validity tests, such Pcvenule recordings were compared with simultaneous estimates of capillary pressure (Pc) with the isogravimetric technique (Pciso) and, further, with data for experimentally evoked changes of Pc derived from volumetric recordings of net transvascular fluid flux divided by the capillary filtration coefficient (delta Pcvol). Simultaneously obtained data for Pcvenule and Pciso showed close agreement, and the Pcvenule and Pcvol data showed a highly significant linear correlation over a wide range of Pc changes. These results indicate that reliable estimates of Pc can be obtained with the Pcvenule method. It allows for continuous Pc recordings without interfering with normal vascular reactivity and can be applied to non-isogravimetric conditions and combined with simultaneous observations of whole-organ transvascular fluid exchange. At normal arterial and venous pressures and vascular tone, Pcvenule averaged 16.2 +/- 0.2 mm Hg, at which a Starling fluid equilibrium prevailed, and increased with decreasing vascular tone, resulting in net transvascular fluid filtration.

Effects of selective ETB‐receptor stimulation on arterial, venous and capillary functions in cat skeletal muscle

“…Observations were made on the acutely sympathectomized lower leg muscles of the right hindlimb, a preparation described in detail elsewhere (Mellander et al, 1987). In brief, the muscle region was auto-perfused in situ via an arterial shunt placed between the femoral and popliteal artery.…”

“…In brief, the muscle region was auto-perfused in situ via an arterial shunt placed between the femoral and popliteal artery. The muscle preparation, with intact arterial and venous supply, was enclosed in a Ringer fluid-filled plethysmograph, using special cannulation and instrumentation techniques described in detail elsewhere (Mellander et al, 1987;Bjornberg et al, 1988). With this method, it is possible to obtain reliable continuous recordings of the following circulatory variables: arterial, arteriolar, capillary and venous pressures, regional blood flow, net transcapillary fluid flux, and resistances in the whole muscle vascular bed (RT) and in the following consecutive vascular sections: large-bore arterial resistance vessels (>25 ,sm; Raprox), small arterioles (<25 gsm; a and the veins (Rv).…”

Effects of increased and decreased tissue pressure on haemodynamic and capillary events in cat skeletal muscle.

“…In brief, the LG muscle is supplied by two segmental vascular circuits emanating from two side branches of the sural artery, of which the proximal circuit forms the dominating nutritional supply. Essential for the microvessel pressure measurements was the morphologically and functionally demonstrated existence of highly regular microvascular anastomotic connections between these two segmental vascular circuits (Mellander et al 1987a;Bjornberg et al 1988 (Mellander et al 1987a;Maspers, Bjornberg & Mellander, 1990;Mellander & Bjornberg, 1992 (Fig. 3).…”

“…Skeletal muscle preparation Observations were made on the acutely sympathectomized lower leg muscles of the right hindlimb, surgically prepared as described in detail elsewhere (Mellander, Bjornberg, Maspers & Myrhage, 1987a). In brief, the skin was dissected free of the hindlimb muscles down to the ankle, and the paw was removed at the ankle joint.…”

“…Measurements of capillary and arteriolar pressures were made from the lateral head of the gastrocnemius (LG) muscle according to a special microcannulation technique described in detail elsewhere (Mellander et al 1987a;Bjornberg, Grande, Maspers & Mellander, 1988). In brief, the LG muscle is supplied by two segmental vascular circuits emanating from two side branches of the sural artery, of which the proximal circuit forms the dominating nutritional supply.…”