title: Sieving of electrolytes at capillary wall of cat skeletal muscle by osmotic water flow.
abstract: To test the hypothesis that a significant proportion of transcapillary water flow occurs through solute-restricting channels, we investigated the effects of transcapillary water movement on plasma electrolytes in isolated perfused cat skeletal muscle. The lower hindlimbs of anesthetized cats were perfused with a plasma-albumin solution and were weighed to determine transcapillary water movement. Osmolality was increased 60-70 mosmol/kgH2O with sucrose, creating water fluxes of 8-10 ml.min-1.100 g-1, and the changes in the venous concentrations of sodium, potassium, and chloride were determined. The ion concentrations were all reduced by 6-7% with no significant difference between them. The amount of reduction was quantitatively explained by the flow of ion-free water from the interstitial space into plasma and the diffusion of electrolyte in the same direction. These findings support the hypothesis that important water-only transcapillary channels exist in mammalian skeletal muscle. The observations may also explain some of the electrolyte changes seen in intense exercise.
authors.affiliation: Department of Physiology, University of South Carolina, Columbia 29208.
authors.forename: P D
authors.initials: PD
authors.lastname: Watson
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism*; D002196:Capillaries / Q000378:metabolism; D002199:Capillary Permeability; D002415:Cats; D004573:Electrolytes / Q000097:blood*; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D009132:Muscles / Q000098:blood supply*; D009995:Osmosis
chemical_list: D004573:Electrolytes