Am. J. Respir. Crit. Care Med., Vol 150, No. 6, 12 1994, 1605-1611.
Hyaluronan efflux from canine lung with increased hydrostatic pressure and saline loading
MI Townsley, RK Reed, M Ishibashi, JC Parker, TC Laurent and AE Taylor
Department of Physiology, University of South Alabama, Mobile 36688.
Although lymphatic washout of hyaluronan during lung hydration has been
postulated to deplete lung interstitial hyaluronan content and thereby
contribute to the decreased interstitial exclusion of albumin observed
under these conditions, this hypothesis has not been directly tested. In
anesthetized, ventilated mongrel dogs, a prenodal lung lymphatic was
cannulated for measurement of lymph flow and hyaluronan concentration.
Following baseline measurements, Pla was increased in four steps of 5 cm
H2O in Group 1 or set to one pressure ranging between 6 and 32 cm H2O in
Group 2. In Group 3, saline (15% body weight) was infused over 30 min and
then Pla increased as in Group 2. Invariably, as lymph flow increased in
Groups 1 through 3, lymph hyaluronan concentration and hyaluronan flux
increased significantly (p < 0.05). In a separate control group, there
were no changes in lymph flow, hyaluronan concentration, or hyaluronan
flux. In Group 3, lung hyaluronan content at 5 h (0.76 +/- 0.08 mg/g dry
weight) was not significantly less than that during baseline (0.88 +/- 0.05
mg/g dry weight), although total uronic acid content actually increased by
38% over the same time course. In contrast, in the control group, both lung
hyaluronan and uronic acid content remained stable over the experimental
period. From these data, approximately 2 to 3% of lung hyaluronan is
predicted to leave the interstitium via lymphatic flux per day under
baseline conditions. The daily turnover of interstitial hyaluronan by this
route increased to 15 to 18% of total content when Pla was elevated and to
54% following saline infusion. Thus, lung hyaluronan can be rapidly
mobilized with increased lymph flow.(ABSTRACT TRUNCATED AT 250 WORDS)
