Spontaneous activity in isolated bovine mesenteric lymphatics

225

262

SUMMARY1. Isolated preparations of bovine mesenteric lymphatics containing about seven valved segments were cannulated and set up in a perfusion system so that, when the preparation was not contracting, the inflow and outflow pressures were exactly equal and there was no flow through the preparation.2. Transmural pressure was varied by raising or lowering the inflow and outflow pressures simultaneously by the same amount.3. The isolated vessels showed rhythmic spontaneous activity; it consisted of quick contractions which spread rapidly over the entire preparation, each followed by a rapid relaxation and a diastolic pause.4. With each contraction, the preparation decreased in both length and diameter and generated an outflow pressure which pumped fluid in the direction determined by the orientation of the values.5. Raising the transmural pressure in the preparation increased the output of the preparation; this was achieved by an increase in both the frequency and force of the individual contractions.6. It was concluded that bovine lymphatics could propel fluid by their intrinsic activity at a rate which was related to the degree of distension of their walls.

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

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

McHale¹,

Roddie²

1976

225

262

“…When tone was reduced, Jl did not change with isoprenaline, decreased with pentobarbitone or with isotonic solutions of MgSO4, mannitol, or glucose as the serosal fluid (Table 2), but appreciably increased with noradrenaline and adrenaline. The increase of Jl by the latter could be related to their effects on the increases in mesenteric lymphatic contractility (Florey, 1927;Ohhashi, Kawai & Azuma, 1978;Mawhinney & Roddie, 1973) which may promote lymph flow. When the luminal fluid was isotonic MgSO4 or LiCl solution, fluid was secreted into the lumen of the intestine and motility was increased to 2-3 +, but Jl was 0 in both cases.…”

Section: Discussionmentioning

confidence: 99%

Relationship between intestinal motility, tone, water absorption and lymph flow in the rat.

Lee¹

1983

SUMMARY1. The relations between motility, tone, water absorption rate (J,) and lymph flow (J,), were studied in an exteriorized upper jejunal preparation in vivo, with its serosal side bathed in Krebs-Ringer or other solutions. Neither J, nor J, was correlated with motility.2. When the luminal fluid consisted of an isotonic solution of MgSO4, glucose or LiCl, motility was greatly increased with no increase in J1.3. When the serosal fluid consisted of an isotonic solution of mannitol, glucose or MgSO4, motility was depressed with a large decrease in tone, and J, was increased by 51-83 % with a decrease in J,. When the serosal fluid consisted of an isotonic solution of NaCl, Na2SO4, LiCl or KCl, motility was decreased with either no change or an increase in tone, and both J, and J, were much decreased. When isotonic cholihe Cl solution was employed as the serosal fluid, motility increased with an increase in tone, J, became negative (fluid secretion), and J, decreased to 0. 4. Acetylcholine depressed motility but increased tone with a decrease in Jv and J,. Eserine increased both tone and motility with a decrease in Jv and Ji. Serotonin caused no change in motility but increased tone with a decrease in J4 and J,.Noradrenaline and adrenaline depressed motility and reduced tone with an increase in Jv and Ji. Isoprenaline abolished motility and reduced tone with a large increase in Jv but no change in J,. Pentobarbitone depressed motility and reduced tone with an increase in Jv but a decrease in J,.5. It is concluded that the intestine responds to various stimuli with a change in motility, or tone, or both. Intestinal motility per se does not produce lymph. Since an increase or decrease in tone always results in a decrease or increase in J, respectively, regardless of the nature of the conditions, a relaxation of the intestinal musculature appears to be associated with an increase in water absorption.

“…into rat mesentery was followed N. G. McHALE AND I. C. RODDIE by a vigorous contractile spasm of the lacteals near the injection site and a much increased rate of contraction further away. Mawhinney & Roddie (1973) found that noradrenaline had the effect of increasing the frequency of longitudinal contraction of isolated segments of bovine mesenteric lymphatic. Amplitude of contraction decreased as well, but less would have been predicted for a comparable spontaneous rate increase.…”

Section: Introductionmentioning

confidence: 99%

The effects of catecholamines on pumping activity in isolated bovine mesenteric lymphatics.

McHale¹,

Roddie²

1983

SUMMARY1. Bovine mesenteric lymphatics of 8 cm length were cannulated and arranged so that pressure changes produced by spontaneous contractions and accompanying flow could be measured.2. The mean frequency of spontaneous contractions, although constant for any one vessel, varied between vessels from 0-5 to 5-2 beats/min (mean 2-6, S.D. 1-6, n = 33).3. Noradrenaline (100 ng/ml.) invariably increased frequency of contractions but flow was increased only in those vessels which had a low resting frequency.4. In those vessels which had a higher resting frequency, flow was decreased despite the increase in frequency because stroke volume decreased. This may have been due to increased pace-maker activity causing desynchronization of the contractile activity in the vessel wall and thus decreased effectiveness of pumping.5. High doses (> 1 jug/ml.) of noradrenaline invariably depressed flow. 6. Isoprenaline slowed the frequency of spontaneous contractions and this either had little effect on flow (due to an increased filling time and thus stroke volume) or depressed it, finally abolishing it entirely at higher doses.7. It is concluded that in suitable dosage (which varies for different vessels) noradrenaline is capable of enhancing flow and this might, at least in part, explain the increase in lymph flow resulting from noradrenaline infusion in living animals.