Aerobic metabolism on muscle contraction in porcine iris sphincter.

Musashino/Tokio – mechentel news – Eyes are supplied O2 through the cornea and vessels of the retina and iris, which are tissues characterized by aerobic metabolism. Meanwhile, there are no reports on the association between iris sphincter contraction and aerobic metabolism. In this paper, we studied the aforementioned association. Eyes from adult pigs of either sex were obtained from a local abattoir. A muscle strip was connected to a transducer to isometrically record the tension. O2 consumption was measured using a Clark-type polarograph connected to a biological oxygen monitor. Creatine phosphate (PCr) and adenosine triphosphate (ATP) contents were measured in the muscle strips by high-performance liquid chromatography (HPLC). Irissphincter muscles were measured in resting, contractile or hypoxic phases. Contraction was induced by hyperosmotic 65 mM KCl (H-65K+) or carbachol (CCh), and hypoxia was induced by aeration with N2 instead of O2 or by addition of sodium cyanide (NaCN). H-65K+- and CCh-inducedmuscle contraction, which involved increasing O2 consumption. Hypoxia and NaCN significantly decreased H-65K+- and CCh-induced musclecontraction and/or O2 consumption and PCr contents. Our results suggest that the contractile behavior in porcine iris sphincter highly depends on mitogen oxidative metabolism. (pubmed, mm)

Autors Kanda H, Kaneda T, Kato A, Yogo T, Harada Y, Hara Y, Urakawa N, Shimizu K. Correspondence: Takeharu Kaneda, Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Nippon Veterinary and Life Science University, 7-1 Kyonan-cho 1-chome, Musasino, Tokyo 180-8602, Japan. Electronic address: t-kaneda@nvlu.ac.jp. Study: Aerobic metabolism on muscle contraction in porcine iris sphincter. Sources: J Vet Med Sci. 2016 Aug 9. [Epub ahead of print]. Web: https://www.jstage.jst.go.jp/article/jvms/advpub/0/advpub_16-0175/_article.