To determine whether fiber type-specific expression of heat shock protein (HSP, or stress protein) occurs in unstressed rat skeletal muscle, the medial gastrocnemius of adult female Sprague-Dawley rats was subjected to immunohistochemical analysis. Antibodies against 5 types of anti-myosin heavy chain (MHC) were used to classify the type of fibers, and 2 types of anti-HSP antibodies were employed to analyze the fiber type-specific expression.
Serial cross-sections of 10 μm thick cut by a cryostat were incubated with primary anti-MHC or anti-HSP 60 and 72 antibodies, followed by biotinylated secondary anti-mouse antibodies, and avidin-biotin complex solution. A peroxidase DAB substrate kit (Vector SK-4100) or BCIP/NBT solution was used to visualize the immunoreaction of each fiber type.
By using the 5 types of anti-MHC antibodies, fibers were classified into 4 types : slow-type I, fasttypes IIA, IIX, and IIB. Anti-HSP 72 antibody reacted with many, but not all, type I and IIA fibers, whereas anti-HSP 60 antibody reacted specifically with type I fibers. Neither type IIX nor IIB fibers showed immunoreactivity with anti-HSP 60 or 72 antibodies. These results suggest that the expression of HSP 60 protein is related to that of type I MHC, and that the expression of HSP 72 protein may be related to that of types I and ha MHC, in unstressed rat skeletal muscle.

Evidence of an increased resting blood flow in the tendon against the adjacent muscle was confirmed in the in situ hindlimb preparation of a rabbit anesthetized with urethane. The tendon tissue blood flow was found to be modulated by nervous and mechanical factors. The effect of nervous control was demonstrated by the denervation of the sciatic nerve, which showed a gradual increase in the resting blood flow in the tendon and muscle after being severed. During local muscle exercise, the increase of tendon tissue blood flow observed was minimal in comparison with the adjacent muscle. The tendon surrounding tissue blood flow showed site-dependent characteristics along the longitudinal tendon bundles. Evidence of tendon vascular structure in the rabbit species was confirmed by observing capillaries in cross sectional fascicles and longitudinal and transversal vessels in the paratenon of the Achilles tendon. These results strongly suggest a physiological model of local tissue temperature regulation and fluid dynamics in the biological system.

Lower-extremity antigravity muscle contraction (the static muscle pump and muscle mechanoreflex) and the baroreflex are involved in regulating blood pressure (BP) during upright standing. We hypothesized that in females with orthostatic hypotension (showing a decrease > 20/10 mmHg within 3 min upon standing from supine), the muscle pump and mechanoreflex of the antigravity muscles is small during upright standing in those who have not undergone exercise training. To test this hypothesis, we compared the cardiovascular responses to head-up tilt, head-up suspension, head-up tilt + venous occlusion (which stops venous return from the lower extremities by static muscle pump), and head-up suspension + venous occlusion of 14 young females with orthostatic hypotension, of which seven had undergone exercise training (tOH) and seven had not (uOH), with those of eight females with orthostatic normotension (control) who had not undergone exercise training. Changes in BP, heart rate (HR), and stroke volume (SV) during both head-up tilt and suspension were measured. Although the increase in HR was larger and the decrease in SV tended to be smaller during head-up tilt than during suspension in the tOH, the response patterns of both were the same in the uOH. In occlusion trials, the increase in HR was larger during head-up tilt than during suspension in the tOH, whereas the increases in HR in both scenarios were the same in the uOH. These findings suggest a small muscle mechanoreflex of the antigravity muscles during upright standing in females with orthostatic hypotension who have not undergone exercise training.