In order to assess the effects of irradiation on lymphatic function, the contraction frequency and maximum and minimum diameters of guinea pig mesenteric collecting lymphatic vessels were measured in viva 4 hours after 1000 rads of abdominal irradiation. The mean contraction frequency for lymphatics from irradiated guinea pigs (7.6±0.7) was significantly higher than for normals (non-irradiated) (4.7±0.7) during an initial control observation period, but there was no difference in maximum or minimum diameter between the two groups during this period. Topical application of 10-4M noradrenaline (NA) significantly increased contraction frequency in both groups; lymph vessel diameter significantly decreased after NA in irradiated, but not in normal guinea pigs. Intravenous infusion of calcium dobesilate (200 mg/kg) caused a significant increase in the contraction frequency of lymphatic vessels in both normal (to 9.4±1.5) and irradiated (to 9.8±1.2) animals, but diameter was not significantly altered. Thus, lymphatic vessels from irradiated guinea pigs were still responsive to exogenous stimuli 4 hours post-irradiation and were initially pumping more actively than those from normal guinea pigs, presumably in response to radiation-induced edema. They also exhibited a supersensitivity to the vasoconstrictive effects of NA, perhaps due to an alteration of the pacemaker or smooth muscle cells by irradiation.
|Number of pages||8|
|Publication status||Published - Dec 1994|