Observations on the contractility of lacteals

Abstract

THE appearances presented by the lacteals on microscopic examination of the mesentery in the guinea-pig and rat have been described in a. previous communication(i). The rhythmical activities of these vessels have been examined, from the point of view of their initiation and control, both by means of nerve stimulation and drug action. The appearances and reactions presented by the lacteals and lymph glands of other species are also described.It was possible with the microdissection apparatus to inject minute quantities of a drug close to the lacteal under observation, so that the effects of such an application could be seen on a circumscribed portion of the lacteal. The pipette was first filled with the drug and the mesentery spread above the hollow chamber. By suitable manipulation the drug was then injected and the results watched. The drugs chosen were pilocarpine and adrenalin, as it was possible that the reactions obtained with them would give some indication of nervous influences on the rhythm. Pituitrin was also used.In the rat, the injection of a small quantity of 1/100,000 adrenalin was followed by a vigorous contractile spasm in portions just near the injection and a much increased rate of contraction in portions a little further away. The rate of contraction rose from once in 5 or 6 seconds to twice per second on occasion. It must be admitted, however, that the reactions presented by these vessels were liable to be capricious, as also is the case in the cat, which will be described later. This effect on the rhythm could not be produced in all experiments but, in that it occurred quite frequently, it must be accepted as significant. The negative results may be attributable to some unknown factor, inflammation possibly, as it is known that blood vessels in a state of inflammation do not react by contraction to adrenalin. In these preparations the blood vessels reacted invariably, but the lacteals seem to be possessed of a more delicate contractile mechanism.PH. LXIII.

The role of external compression and movement in lymph propulsion in the sheep hind limb.

“…Movement of lymph depends upon forces outside the lymphatic system'. This conviction seems curious bearing in mind that Hewson (1774) and Florey (1927) had already observed that lymphatic ducts were rhythmically contractile. However, even today, the idea that a small pressure gradient from lymph capillary to central veins (vis a tergo) and the massaging effects of arterial pulsation and muscular contractions are primarily responsible for lymph propulsion is so intuitively appealing that it has been a difficult one (in the words of Staub & Albertine, 1985) 'to extirpate from the literature'.…”

The effect of transmural pressure on pumping activity in isolated bovine lymphatic vessels.

“…Rhythmic contractions have been observed in many varieties of lymph vessels in vivo (Hewson, 1774;Florey, 1927;Smith, 1949;Kinmonth & Taylor, 1956). Hall, Morris & Wooley (1965) established lymphatic fistulae in conscious sheep and recorded pulsatile pressures ranging from 1 to 25 mmHg at frequencies from 1 to 30/min.…”

ET‐1‐associated vasomotion and vasospasm in lymphatic vessels of the guinea‐pig mesentery

“…Many lymphatic and blood vessels exhibit vasomotion, a rhythmic constriction -dilation cycle of these vessels (Florey, 1927;Johnson, 1980). This mechanism is responsible for both the propulsion of lymph (each phasic constriction pumping lymph forward through unidirectional valves within lymphatic vessels; Mislin, 1983;Johnston & Elias, 1987;McHale, 1990), and for modulating the local vascular resistance and blood flow (see Haddock et al, 2002).…”