title: Inhomogeneous vasodilatory responses of rat tail arteries to heat stress: evaluation by synchrotron radiation microangiography.
abstract: Tail blood flow is crucial for dissipating body heat in rats. Angiographies are convenient tools to evaluate tail circulation. However, conventional angiographies do not have sufficient sensitivity or spatial resolution for small vessels. Recently, we developed a novel microangiographic system using monochromatic synchrotron radiation and a high-definition video camera system. Here, we report an evaluation of rat tail circulation under heat stress using the synchrotron radiation microangiographic system. We performed an experiment using the microangiography of the caudal artery before and after heating up WKAH/HkmSlc rats to rectal temperature of 39 degrees C. The images were digitized and temporal subtraction was performed, and the diameters of caudal arteries were evaluated. After heating, the medial caudal artery was markedly dilated (320 +/- 53 to 853 +/- 243 micro m in diameter, p<0.001), while no significant change was observed in the lateral caudal arteries (139 +/- 42 to 167 +/- 73 micro m) and segmental anastomosing vessels. The heat stress allowed for visualization of the superficial caudal arteries with a diameter of approximately 60 micro m, not visible prior to heating. Thus, synchrotron radiation microangiography demonstrated that the rat tail possessed dual sets of arteries; one set was highly sensitive to heat-induced vasodilation (medial caudal artery and superficial caudal arteries) and the other set was less sensitive (lateral caudal arteries and segmental anastomosing vessels).
authors.affiliation: Department of Surgery, Tokai University School of Medicine, Isehara, 259-1193 Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Kuwabara
authors.forename: Fujiya
authors.initials: F
authors.lastname: Furuyama
authors.forename: Kunihisa
authors.initials: K
authors.lastname: Ito
authors.forename: Etsuro
authors.initials: E
authors.lastname: Tanaka
authors.forename: Naoichiro
authors.initials: N
authors.lastname: Hattan
authors.forename: Hisanori
authors.initials: H
authors.lastname: Fujikura
authors.forename: Koji
authors.initials: K
authors.lastname: Kimura
authors.forename: Takako
authors.initials: T
authors.lastname: Goto
authors.forename: Takashi
authors.initials: T
authors.lastname: Hayashi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Taira
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Shinozaki
authors.forename: Keiji
authors.initials: K
authors.lastname: Umetani
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Hyodo
authors.forename: Kenkichi
authors.initials: K
authors.lastname: Tanioka
authors.forename: Ryo
authors.initials: R
authors.lastname: Mochizuki
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kawai
authors.forename: Shirosaku
authors.initials: S
authors.lastname: Koide
authors.forename: Hidezo
authors.initials: H
authors.lastname: Mori
mesh_terms: D000792:Angiography; D015901:Angiography, Digital Subtraction; D000818:Animals; D001158:Arteries; D006358:Hot Temperature; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000503:physiopathology*; D017356:Synchrotrons; D013623:Tail / Q000098:blood supply*; D014664:Vasodilation