ROLE OF THE INTERSTITIAL MATRIX AND LYMPHATIC PUMP IN REGULATION OF TRANS-CAPILLARY FLUID BALANCE

Blood/tissue fluid balance is governed by forces generated within the capillary, interstitial, and lymphatic compartments. This paper focuses on the role of the extracellular matrix and myogenic lymph pump in automatic control of transcapillary fluid movement. The physicochemical properties of the extracellular matrix determine the pressure and compliance of the interstitial spaces. In addition, the dependence of interstitial protein exclusion on matrix hydration amplifies the extent of oncotic buffering induced by interstitial volume alterations. Distension of muscular lymph vessels elicits increases in contraction frequency, stroke volume, and lymph flow. Thus, the rate of lymphatic removal of interstitial water and protein is geared to the state of hydration of the interstitial matrix. These interstitial and lymphatic compensatory reactions are important components of the margin of safety" against edema formation. © 1979."