Effect of the Pulse on Lymph Formation and Interstitial Movement of Substances

The results of recent investigations suggest that connective tissue fibers serve as pathways for the extravascular transport of vital dyes escaping from lymphatics. 1 In unpublished studies on the ear of the mouse, gentle, alternating, external pressures (0 to 2 cm. or 8 cm. of water) caused squeezing of the tissues and bending of these fibers and at the same time the rapidity of spread of vital dyes through the interstitial tissues was increased. That gentle massage increases the lymph flow from a part is well known. 2 The work to be reported now deals with the effect of pulsation of the blood vessels both upon lymph flow and upon the movement of substances through the interstitial tissues.

Warmed, defibrinated, aerated rabbit's blood was perfused for periods of 1 to 1 1/2 hours, through freshly cannulated rabbit's ears, with the use of an apparatus providing pulsatile and non-pulsatile pressures. “Systolic” and “diastolic” pressures of 141/60 mm. of mercury were used in the case of the pulsatile pressure at about 100 “beats” per minute, while for the constant pressure the equivalent of 141 mm. of mercury was employed. It will be seen that a somewhat higher mean pressure was used in the latter instances. Lymph formation and flow were estimated by filling a few peripheral lymphatics near the tip of the ear with a vital dye and noting the movement of the dye colored lymph toward the base of the ear. The method has been previously used in human skin. 2 To study the rate of spread of substances through the tissues, minute amounts (0.01 to 0.02 cu. mm.) of a vital dye (pontamine sky blue) were introduced through micropipettes into the subepidermal connective tissue of the ear by capillarity without utilization of pressure, Camera lucida drawings of the outline of the dye spots were made immediately after placing the dye in the tissues and again half an hour and 1 hour later.