title: In vivo micro-circulation measurement in skeletal muscle by intra-vital microscopy.
abstract: BACKGROUND
  Regulatory factors and detailed physiology of in vivo microcirculation have remained not fully clarified after many different modalities of imaging had invented. While many macroscopic parameters of blood flow reflect flow velocity, changes in blood flow velocity and red blood cell (RBC) flux does not hold linear relationship in the microscopic observations. There are reports of discrepancy between RBC velocity and RBC flux, RBC flux and plasma flow volume, and of spatial and temporal heterogeneity of flow regulation in the peripheral tissues in microscopic observations, a scientific basis for the requirement of more detailed studies in microcirculatory regulation using intravital microscopy.
  
  
  METHODS
  We modified Jeff Lichtman's method of in vivo microscopic observation of mouse sternomastoid muscles. Mice are anesthetized, ventilated, and injected with PKH26L-fluorescently labeled RBCs for microscopic observation.
  
  
  CONCLUSIONS
  Fluorescently labeled RBCs are detected and distinguished well by a wide-field microscope. Muscle contraction evoked by electrical stimulation induced increase in RBC flux. Quantification of other parameters including RBC velocity and capillary density were feasible. Mice tolerated well the surgery, injection of stained RBCs, microscopic observation, and electrical stimulation. No muscle or blood vessel damage was observed, suggesting that our method is relatively less invasive and suited for long-term observations.
authors.affiliation: Department of Anesthesiology and Critical Care, Shriners Hospital for Children, Massachusetts General Hospital, and Harvard Medical School, USA.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Asai
authors.forename: Nita
authors.initials: N
authors.lastname: Sahani
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Ouchi
authors.forename: Jeevendra
authors.initials: J
authors.lastname: Martyn
authors.forename: Shingo
authors.initials: S
authors.lastname: Yasuhara
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D004558:Electric Stimulation; D004912:Erythrocytes / Q000502:physiology; D005456:Fluorescent Dyes; D051379:Mice; D008833:Microcirculation; D008853:Microscopy / Q000379:methods*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000502:physiology
chemical_list: D005456:Fluorescent Dyes