title: The effects of radiation on the contractile activity of guinea pig mesenteric lymphatics.
abstract: 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 vivo 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(-4) M 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.
authors.affiliation: Department of Anatomy, Flinders University, South Australia.
authors.forename: A M
authors.initials: AM
authors.lastname: McMahon
authors.forename: C J
authors.initials: CJ
authors.lastname: Carati
authors.forename: N B
authors.initials: NB
authors.lastname: Piller
authors.forename: B J
authors.initials: BJ
authors.lastname: Gannon
mesh_terms: D000818:Animals; D002123:Calcium Dobesilate / Q000494:pharmacology; D006168:Guinea Pigs; D008196:Lymph; D008208:Lymphatic System / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D008643:Mesentery / Q000033:anatomy & histology; D009638:Norepinephrine / Q000494:pharmacology; D013997:Time Factors
chemical_list: D002123:Calcium Dobesilate; D009638:Norepinephrine