Distally based anterolateral thigh flap: an anatomic and clinical study

The distally based anterolateral thigh flap has been used for coverage of soft-tissue defects of the knee and upper third of the leg. This flap is based on the septocutaneous or musculocutaneous perforators derived from the lateral circumflex femoral system. The purpose of this study was to examine the results of anatomical variations of the descending branch of the lateral circumflex femoral artery and the retrograde blood pressure of the descending branch of the lateral circumflex femoral artery so that the surgical technique for raising and transferring a distally based anterolateral thigh flap to the knee region could be improved. The authors have actually used this flap in three cases. In 11 thighs of six cadavers, the descending branch of the lateral circumflex femoral artery had a rather consistent connection with the lateral superior genicular artery or profunda femoral artery in the knee region. The pivot point, located at the distal portion of the vastus lateralis muscle, ranges from 3 to 10 cm above the knee. In their three cases, the maximal flap size was 7.0 x 16.0 cm and was harvested safely, without marginal necrosis. The mean pedicle length was 15.2 +/- 0.7 cm (range, 14.5 to 16 cm). The average proximal and distal retrograde blood pressure of the descending branch of the lateral circumflex femoral artery was also studied in another 11 patients, and the anterolateral thigh flap being used for reconstruction of head and neck defects showed 58.3 and 77.7 percent of proximal antegrade blood pressure, respectively. The advantages of this flap include a long pedicle length, a sufficient tissue supply, possible combination with fascia lata for tendon reconstruction, and favorable donor-site selection, without sacrifice of major vessels or muscles.     

Use of the free vastus lateralis flap in skull base reconstruction

Free flaps in skull base reconstruction are indicated for providing an effective separation of the intracranial cavity from the oronasal space, for eliminating a dead space, and for the treatment of established wound complications such as dural exposures and cerebrospinal fluid leaks. Seven patients with cranial base defects underwent reconstructions using a free vastus lateralis muscle flap. In two cases, a vastus lateralis flap was raised to incorporate the anterolateral thigh skin as a myocutaneous flap. In four cases, a free flap was indicated for reconstruction following tumor ablation, and in three cases, for the resolution of wound or cerebrospinal fluid leak complications following previous cranial base surgery. All flaps were successful, with no partial failures. In those patients undergoing tumor ablative surgery, the cranial cavity was effectively sealed from the oronasal cavity. Patients with established wound complications following previous cranial base surgery had a complete resolution of their symptoms. This report discusses the suitability of the vastus lateralis flap for skull base reconstruction in terms of the availability of adequate muscle volume to fill dead space, vascularized fascia to augment dural repairs, and the freedom to use skin if required for internal lining or external skin cover. This flap also provides an extremely long pedicle, allows simultaneous flap harvest, and has low donor site morbidity.     

Anterolateral thigh flap donor-site complications and morbidity

The authors examined donor-site complications and morbidity in 37 patients after reconstruction with free or pedicled anterolateral thigh flaps. Intraoperative assessment included damage to the vastus lateralis muscle and whether the main pedicle of the rectus femoris muscle had been killed. Postoperative assessment of the donor site included wound healing, range of motion, muscle strength, gait, and sensation. Patients were surveyed with a questionnaire about fatigue in their activities of daily life and the appearance of the donor site. All 32 patients who underwent primary skin closure could perform activities of daily life normally, and most (87.5 percent) reported that donor-site appearance was satisfactory. However, the severity of donor-site dysfunction was related to the degree of damage to the vastus lateralis muscle, and most patients (87.5 percent) had some loss of sensation at the anterolateral aspect of the thigh. Because of adhesions between the meshed skin graft and the underlying fascia, range of motion at the hip and knee was limited in significantly more patients who had received split-thickness skin grafts (60 percent) than patients who had undergone primary skin closure (3.1 percent). Therefore, wider flaps or flaps harvested nearer the knee may increase donor-site morbidity. The authors concluded that the incidence of long-term morbidity with the anterolateral thigh flap is low, although it is increased when the flap includes the vastus lateralis muscle or is wider and requires additional skin grafting at the donor site.     

Use of vastus lateralis muscle flap for repair of trochanteric pressure sores.

The use of a vastus lateralis muscle flap is suggested as an approach to the surgical repair of trochanteric pressure sores in paraplegic patients. The details of the anatomy of the muscle are outlined, and our surgical technique for its use is described.     

Free anterolateral thigh flap for extremity reconstruction: clinical experience and functional assessment of donor site

From August of 1995 through July of 1998, 38 free anterolateral thigh flaps were transferred to reconstruct soft-tissue defects. The overall success rate was 97 percent. Among 38 anterolateral thigh flaps, four were elevated as cutaneous flaps based on the septocutaneous perforators. The other 34 were harvested as myocutaneous flaps including a cuff of vastus lateralis muscle (15 to 40 cm3), either because of bulk requirements (33 cases) or because of the absence of a septocutaneous perforator (one case). However, vastus lateralis muscle is the largest compartment of the quadriceps, which is the prime extensor of the knee. Losing a portion of the vastus lateralis muscle may affect knee stability. Objective functional assessments of the donor sites were performed at least 6 months postoperatively in 20 patients who had a cuff of vastus lateralis muscle incorporated as part of the myocutaneous flap; assessments were made using a kinetic communicator machine. The isometric power test of the ratios of quadriceps muscle at 30 and 60 degrees of flexion between donor and normal thighs revealed no significant difference (p > 0.05). The isokinetic peak torque ratio of the quadriceps and hamstring muscles, including concentric and eccentric contraction tests, showed no significant difference (p > 0.05), except the concentric contraction test of the quadriceps muscle, which revealed mild weakness of the donor thigh (p < 0.05). In summary, the functional impairment of the donor thighs was minimal after free anterolateral thigh myocutaneous flap transfer.     

The free vastus lateralis flap: an anatomic study with case reports.

The suitability of the thigh as a donor site for a new free flap was examined in 100 cadavers. It was found that the vastus lateralis muscle can be used to form a myocutaneous or fasciomuscular flap, the raising of which causes no technical problems and leads to no functional and only minor aesthetic impairments. Depending on the muscle segment from which the flap is raised, a neurovascular pedicle measuring between 8 and 20 cm with a diameter of 2 to 2.5 mm (artery) or 2.5 to 4 mm (vein) can be formed. The skin island in the myocutaneous flap measures on average 8 x 16 cm and is located above the middle portion of the muscle. The diameter of the supplying perforator vessel is between 0.7 and 1.2 mm. The flap can be raised parallel to head and neck surgery and applied as a myocutaneous flap for coverage of extensive or perforating defects or intraorally as a fasciomuscular flap.     

Vascular endothelial growth factor mRNA expression and arteriovenous balance in response to prolonged,submaximal exercise in humans

Angiogenesis, the growth of new blood vessels from existing ones, occurs in the skeletal muscle as an adaptive response to exercise that satisfies the increased requirement of this tissue for oxygen delivery and metabolic processes. Of the factors that have been identified to regulate this process, the endothelial cell mitogen vascular endothelial growth factor (VEGF) has been proposed to play a key role. The aim of this study was to measure the skeletal muscle VEGF mRNA content and arteriovenous protein balance across the working leg in response to a single bout of prolonged, submaximal exercise. Seven physically active males completed 3 h of two-legged kicking ergometry. Muscle biopsies were collected from the vastus lateralis muscle from both working legs, and blood samples were collected from one femoral artery and femoral vein before, during, and in recovery from exercise. We show that the exercise stimulus elicited a decrease in VEGF protein arteriovenous balance across the exercising leg (P = 0.007), and a ninefold elevation in skeletal muscle VEGF mRNA expression (P < 0.001). The changes in VEGF protein balance and mRNA content were most pronounced 1 h after the cessation of exercise. In conclusion, these findings demonstrate that submaximal exercise, suitable for humans with low CV fitness, induces a decrease in VEGF arteriovenous balance that is likely to be of clinical significance in promoting angiogenic effects.     

Two new cutaneous free flaps: the medial and lateral thigh flaps

Two new cutaneous free-flap donor areas are described on the medial and lateral sides of the thigh. The medial thigh flap is supplied by an unnamed artery from the superficial femoral artery and is drained by the accompanying venae comitantes. Its nerve supply is from the medial femoral cutaneous nerve. The lateral thigh flap has its vascular pedicle from the third perforating artery of the profunda femoral artery and its accompanying vein. The lateral femoral cutaneous nerve provides sensation over the area. These flaps provide a large surface area of both skin and subcutaneous tissue without the usual bulk of subcutaneous fat and muscle. Their desirable features include long vascular pedicles with large vessel diameters and potential of being neurovascular flaps with specific sensory nerve supply and predictable anatomy. The principal disadvantage is that the donor site may leave a slight contour defect with primary closure or require grafting when a large flap is taken. We predict that these flaps will become important donor sites for reconstructive problems requiring resurfacing of cutaneous defects in various anatomic areas.     

Cellularity of organs in mature rams of different breeds

The relative importance of cell number and cell size in determining the mass of 16 organs and tissues in mature rams of six different breeds was studied through estimation of organ deoxyribonucleic acid (DNA) content. The mean fleece-free empty body weight (FFEBW) ranged from 54.6 +/- 0.3 kg for Camden Park Merinos to 76.7 +/- 1.6 kg for Strong Wool Merinos. For all organs, mass increased with FFEBW, but the relationship was significant across all sheep for only eight organs (blood, kidney, liver, abomasum, vastus lateralis muscle, skin, perirenal fat and triceps muscle). There were significant differences between breeds in the mass of 11 organs. With four (heart, rumen reticulum, small intestine and testicular fat) this difference was independent of breed differences in FFEBW, whereas with another four (kidney, abomasum, vastus lateralis muscle and skin), it was closely related to FFEBW. Breed differences in the mass of the remaining three organs (blood, liver and perirenal fat) were partly related to FFEBW and partly breed specific. Blood mass increased with FFEBW across all animals, but, within a breed, it declined as FFEBW increased. The increase in the mass of perirenal fat with FFEBW was significantly greater within a breed than between breeds. Cell number increased significantly with the mass of all organs except blood and brain. There were between-breed differences in the number of cells in seven organs (liver, heart, rumen reticulum, abomasum, small intestine, vastus lateralis muscle and skin), which, except for heart, were attributable to between-breed differences in organ mass. With heart, the increase in cell number with organ mass within a breed was greater than across all breeds. Cell size was significantly related to organ mass only with vastus lateralis muscle, spleen, perirenal fat and liver. The relationship for vastus lateralis muscle and spleen was negative, indicating that cells were smaller in larger organs. There were differences between breeds in cell size for heart, vastus lateralis and triceps muscles. These differences for heart and triceps muscle were breed specific, whereas for vastus lateralis muscle it was attributed to breed differences in organ weight. There was a 30-fold range in mean cell size across organs, with adipose tissue having the largest cells, muscle tissue intermediate and visceral tissues the smallest. In general, organ mass is positively related to FFEBW. Cell number, not cell size, is largely responsible for differences in organ mass between mature sheep of different breeds.     

The blood supply of the reverse temporalis muscle flap: anatomic study and clinical implications

Although the reverse temporalis muscle flap has been used clinically, the exact vascular connection between the superficial and deep temporal vessels has not been clearly defined. The purpose of this study was to investigate the vascular territory of the reverse temporalis muscle supplied by the superficial temporal vessels. Six cadaver heads were studied using a colored lead oxide injection through the superficial temporal artery. The specimens were examined macroscopically and radiographically. The reverse temporalis muscle flap was then applied to a clinical case presenting with traumatic anterior skull base defect communicating with the nasal cavity. The cadaver specimens demonstrated that the superficial temporal artery formed an average 1.3 +/- 0.2 cm in width of dense vascular zone, which was located within 1.8 cm below the superior temporal line. The dense vascular network further perfused the anterior and posterior deep temporal arteries and the muscular branch of the middle temporal artery to supply the temporalis muscle. The mean perfused area of the temporalis muscle was 83 percent, ranging from 79 to 89 percent, in five cadaver heads. One cadaver revealed only 55 percent of perfused area in the absence of the muscular branch of the middle temporal artery. The consistent area without perfusion was located in the distal third of the posterior portion of the reverse temporalis muscle. In clinical cases, the reverse temporalis muscle flap was used successfully to obliterate the anterior skull base defect without evidence of muscle flap necrosis. The exact blood supply to the distal third of the posterior portion of the reverse temporalis muscle flap needs to be investigated further in vivo. Particular attention was paid to the inclusion of the muscular branch of the middle temporal artery in this flap to augment the blood supply to the temporalis muscle.     

Free anterolateral thigh flap for reconstruction of head and neck defects following cancer ablation

Thirty-seven consecutive free anterolateral thigh flaps in 36 patients were transferred for reconstruction of head and neck defects following cancer ablation between January of 1997 and June of 1998. The success rate was 97 percent (36 of 37), with one flap lost due to a twisted perforator. The anatomic variations and length of the vascular pedicle were investigated to obtain better knowledge of anatomy and to avoid several surgical pitfalls when it is used for head and neck reconstruction. The cutaneous perforators were always found and presented as musculocutaneous or septocutaneous perforators in this series of 37 anterolateral thigh flaps. They were classified into four types according to the perforator derivation and the direction in which it traversed the vastus lateralis muscle. In type I, vertical musculocutaneous perforators from the descending branch of the lateral circumflex femoral artery were found in 56.8 percent of cases (21 of 37), and they were 4.83 +/- 2.04 cm in length. In type II, horizontal musculocutaneous perforators from the transverse branch of the lateral circumflex femoral artery were found in 27.0 percent of cases (10 of 37), and they were 6.77 +/- 3.48 cm in length. In type III, vertical septocutaneous perforators from the descending branch of the lateral circumflex femoral artery were found in 10.8 percent of cases (4 of 37), and they were 3.60 +/- 1.47 cm in length. In type IV, horizontal septocutaneous perforators from the transverse branch of the lateral circumflex femoral artery were found in 5.4 percent of cases (2 of 37). They were 7.75 +/- 1.06 cm in length. The average length of vascular pedicle was 12.01 +/- 1.50 cm, and the arterial diameter was around 2.0 to 2.5 mm; two accompanying veins varied from 1.8 to 3.0 mm and were suitable for anastomosis with the neck vessels. Reconstruction of one-layer defect, external skin or intraoral lining, was carried out in 18 cases, through-and-through defect in 17 cases, and composite mandibular defect in two cases. With increasing knowledge of anatomy and refinements of surgical technique, the anterolateral thigh flap can be harvested safely to reconstruct complicated defects of head and neck following cancer ablation with only minimal donor-site morbidity.     

Extensor digitorum brevis free flap: anatomic study and further clinical applications

The extensor digitorum brevis muscle flap is reliable, safe, and can be used either as a pedicle or as a free flap with minimal donor site morbidity. To increase the existing knowledge of this flap and to establish further anatomic basis for the design and elevation of the extensor digitorum brevis flap, 26 specimens from 13 fresh cadavers were dissected under 3.5x loupes. The lateral tarsal artery was found to be the main blood supply to the muscle. It has an average diameter of 1.83+/-0.35 mm and a length of 1.89+/-0.69 cm. The dorsalis pedis artery has, at the level of the lateral tarsal artery takeoff, a diameter of 3.25+/-0.62 mm. From this point to the origin of the deep plantar branch, the dorsalis pedis artery has minimal branching, and the surgeon has available an artery homogeneous in diameter that is 6.77+/-0.99 cm in length. Related neurovascular structures (anterior tibial artery and the venae comitantes, dorsalis pedis and first dorsal metatarsal artery, and deep peroneal nerve) were also studied. A safe and reliable harvesting technique and the "T interposed extensor digitorum brevis" technique for sparing the anterior tibial artery are presented, as are clinical case examples on the use of this flap as a flow-through, extensor digitorum brevis-vascularized nerve graft, a combined extensor digitorum brevis-deep peroneal nerve graft, and a bilobed extensor digitorum brevis-dorsalis pedis fasciosubcutaneous free flap.     

Tensor fasciae latae perforator flap for reconstruction of composite Achilles tendon defects with skin and vascularized fascia

The surgical management of large defects of the Achilles tendon and overlying skin is very demanding and necessitates, as a rule, a free vascularized graft. The ideal characteristics of a thin layer of skin and a strong tendon component, combined with a reliable blood supply and minimal morbidity at the donor site, have only been partially met by all previous grafts used in this situation. The authors performed reconstructions in five patients with large defects of the Achilles tendon and overlying skin by using a perforator flap derived from the tensor fasciae latae flap. A vascularized skin-subcutis-fascia lata flap could be raised by dissecting out two to three perforating arteries through the tensor fasciae latae muscle to the ascending branch of the lateral circumflex femoral artery; the muscle was left in situ in the process. All the flaps took well without complications. At final examination after an average of 20 months, the reconstructed Achilles tendon showed good functional results, although there was a 50 to 70 percent reduction in power during plantar flexion when compared with the normal side. A very good aesthetic result could be obtained after a debulking operation was performed on the skin flap.     

The lower trapezius musculocutaneous flap from pedicled to free flap: anatomical basis and clinical applications based on the dorsal scapular artery

The pedicled lower trapezius musculocutaneous flap is a standard flap in head and neck reconstruction. A review of the literature showed that there is no uniform nomenclature for the branches of the subclavian artery and the vessels supplying the trapezius muscle and that the different opinions on the vessels supplying this flap lead to confusion and technical problems when this flap is harvested. This article attempts to clarify the anatomical nomenclature, to describe exactly how the flap is planned and harvested, and to discuss the clinical relevance of this flap as an island or free flap. The authors dissected both sides of the neck in 124 cadavers to examine the variations of the subclavian artery and its branches, the vessel diameter at different levels, the course of the pedicle, the arc of rotation, and the variation of the segmental intercostal branches to the lower part of the trapezius muscle. Clinically, the flap was used in five cases as an island skin and island muscle flap and once as a free flap. The anatomical findings and clinical applications proved that there is a constant and dependable blood supply through the dorsal scapular artery (synonym for the deep branch of the transverse cervical artery in the case of a common trunk with the superficial cervical artery) as the main vessel. Harvesting an island flap or a free flap is technically demanding but possible. Planning the skin island far distally permitted a very long pedicle and wide arc of rotation. The lower part of the trapezius muscle alone could be classified as a type V muscle according to Mathes and Nahai because of its potential use as a turnover flap supplied by segmental intercostal perforators. The lower trapezius flap is a thin and pliable musculocutaneous flap with a very long constant pedicle and minor donor-site morbidity, permitting safe flap elevation and the possibility of free-tissue transfer.     

The use of anterolateral thigh perforator flaps in chronic osteomyelitis of the lower extremity

From April of 2000 to May of 2003, 28 consecutive patients with chronic osteomyelitis of the lower extremity underwent surgical debridement and reconstruction with anterolateral thigh perforator flaps (six cases were combined with vastus lateralis muscle flaps). All wounds were open for a minimum period of 6 weeks (average, 24.7 months; range, 6 weeks to 52 months). The average patient age was 42.8 years (range, 18 to 71 years), there were 21 male and seven female patients, and the average follow-up period was 18.2 months (range, 5 to 41 months). The cause of injury was an open fracture in 10 cases, secondary wound complications after reduction in eight cases, and diabetic foot in 10 cases. The surface defects ranged from 50 to 153 cm. The wounds were debrided an average of 2.5 times and then reconstructed with flap and treated with antibiotics for 6 weeks. Antibiotic beads were used in six cases and secondary bone graft procedures were performed in seven cases 3 months after the flap coverage. All 28 flaps were successful without any signs of recurrences or persistent osteomyelitis, but partial wound dehiscence was observed during early rehabilitation in two cases suspected of delayed healing caused by diabetes. These wounds healed spontaneously. All patients achieved acceptable gait function after rehabilitation. No debulking procedure was necessary in any case. Although the muscle flap is known to provide superior vascular supply, the type of flap used for coverage seems to be less critical in the final outcome, provided that total debridement and obliteration of dead spaces are achieved. A well-vascularized anterolateral thigh perforator flap was successfully used to combat infection and bring stability to wounds with chronic osteomyelitis.     

The anatomic basis for the platysma skin flap

Meticulous anatomic dissection of the vasculature of the superficial anterolateral neck indicates that the platysma and overlying skin are supplied by direct cutaneous arteries measuring 0.5 mm in diameter. The small arteries are branches of the postauricular and occipital arteries in the upper lateral neck, the facial and submental arteries in the upper medial neck, the superior thyroid artery in the middle of the neck, the subclavian artery in the lower medial neck, and the transverse or superficial cervical arteries in the lateral aspect of the neck. These vessels traverse the undersurface of the platysma muscle to provide blood flow to the overlying skin. As opposed to this direct cutaneous system, the myocutaneous blood supply perforating through the sternocleidomastoid is scant. The platysma skin flap will survive if the blood supply from at least one region is preserved. In addition, it may be beneficial to include the external jugular and/or the communicating veins in the flap. By following these guidelines, the platysma flap has been successfully used for facial reconstruction in 7 of 8 consecutive patients.     

Aging affects different human muscles in various ways. An image analysis of the histomorphometric characteristics of fiber types in human masseter and vastus lateralis muscles from young adults and the very old

This study is an attempt to objectively evaluate age-related changes in human muscles by use of histomorphometric methods. Aging in humans induces dramatic transformations in the skeletal muscles but little is known as to whether or not the aging processes per se may affect all muscles equally. In this study aging of two human muscles with different functions, origin and nerve supply is compared. Sections were cut from masseter and vastus lateralis muscles obtained from young adults aged 18-24 years and from the very old aged 90-102 years. Muscle fiber types were classified with the traditional myofibrillar ATPase staining. Various histomorphometric parameters of the different fiber types in human masseter and vastus lateralis muscle sections were obtained by image analyses to evaluate the age-related changes in the muscle fibers. The following variables were calculated: the number of each fiber type per photographed area; the area of each fiber and two indicators for the shape of the muscle fibers. In the aging muscles there was no relative preferential loss of a fiber type. High numbers of intermediate ATPase-stained fibers (IM fibers) were found in some old vastus muscles but were only sporadic in young vastus muscles. However, there was no change in the percentage distribution of intermediate ATPase-stained fibers when young and very old human masseter muscles were compared. Incubation of the sections with antimyosin antibodies showed that the IM fibers in old masseter and old vastus contained different myosin heavy chains. Thus ATPase activity and anti-myosin staining displayed a somewhat different pattern of fiber type distribution. The main changes in the shape and area indicated that type I fibers in the masseter became more circular while in the vastus they decreased significantly in size. The type II fibers in the vastus became very small and deviated significantly from circularity whereas the type II fibers in the masseter only exhibited a decrease in the size of the fibers. Histomorphometric measurements show that aging affects different human muscles in various ways.     

Intraoperative physiologic blood flow studies in the TRAM flap.

An intraoperative study was done to establish the functional and quantitative properties of the blood supply to the TRAM flap through the assessment and manipulation of blood flow through the deep epigastric arterial system. Seventeen patients undergoing unilateral postmastectomy breast reconstruction with lower transverse rectus abdominis myocutaneous (TRAM) flaps were studied. The study is divided into two parts: (1) ultrasonic measurement of blood flow in the deep inferior epigastric artery (DIEA), and (2) direct measurement of blood pressure in the deep epigastric arterial system, after division of the deep inferior epigastric artery. With occlusion of the superior epigastric artery at the level of the upper edge of the skin flap, 71 percent of the patients had a decrease in the blood flow through the deep inferior epigastric artery, with an average decrease of 23 percent. This implies that the area of watershed perfusion in the lower TRAM flap is superior to the umbilicus, and therefore, survival of all lower TRAM flap tissues requires reversal in the normal direction of arterial flow to the flap. The blood pressure in the proximal stump of the deep inferior epigastric arterial system averaged 46 percent of the mean systemic blood pressure. Occlusion of the medial and lateral thirds of the isolated rectus muscle decreased the mean arterial blood pressure in the flap an average of 19 percent in 80 percent of the individuals studied. These data support the technique of harvesting the entire rectus muscle, avoiding muscle-splitting maneuvers that may compromise axial blood flow.     

IL-6 activates HSP72 gene expression in human skeletal muscle

To determine whether the cytokine interleukin (IL)-6 induces heat shock protein (HSP) 72 gene expression in skeletal muscle, 18 healthy, young men had either a high dose of IL-6 (HiIL-6; n=6), low dose IL-6 (LoIL-6; n=6), or saline (CON; n=6) infused into one femoral artery for 3h. Muscle biopsies were obtained from the vastus lateralis of the infusion limb and samples were analyzed for HSP72 mRNA. In addition, blood samples were collected from the femoral vein of the infusion limb and analyzed for plasma IL-6. In CON, femoral vein IL-6 concentration remained at basal levels throughout the experiment but in both HiIL-6 and LoIL-6, femoral vein IL-6 concentrations were markedly elevated (P<0.05). HSP72 gene expression did not increase above resting levels in CON. In contrast, in both HiIL-6 and LoIL-6, HSP72 mRNA increased (P<0.05) 2.5- and 2.3-fold, respectively after 30min of infusion and remained elevated (P<0.05) for 24h following infusion. These data demonstrate that IL-6 can rapidly induce HSP72 gene expression in human skeletal muscle.     

Central command contributes to increased blood flow in the noncontracting muscle at the start of one-legged dynamic exercise in humans

Whether neurogenic vasodilatation contributes to exercise hyperemia is still controversial. Blood flow to noncontracting muscle, however, is chiefly regulated by a neural mechanism. Although vasodilatation in the nonexercising limb was shown at the onset of exercise, it was unclear whether central command or muscle mechanoreflex is responsible for the vasodilatation. To clarify this, using voluntary one-legged cycling with the right leg in humans, we measured the relative changes in concentrations of oxygenated-hemoglobin (Oxy-Hb) of the noncontracting vastus lateralis (VL) muscle with near-infrared spectroscopy as an index of tissue blood flow and femoral blood flow to the nonexercising leg. Oxy-Hb in the noncontracting VL and femoral blood flow increased (P < 0.05) at the start period of voluntary one-legged cycling without accompanying a rise in arterial blood pressure. In contrast, no increases in Oxy-Hb and femoral blood flow were detected at the start period of passive one-legged cycling, suggesting that muscle mechanoreflex cannot explain the initial vasodilatation of the noncontracting muscle during voluntary one-legged cycling. Motor imagery of the voluntary one-legged cycling increased Oxy-Hb of not only the right but also the left VL. Furthermore, an increase in Oxy-Hb of the contracting VL, which was observed at the start period of voluntary one-legged cycling, had the same time course and magnitude as the increase in Oxy-Hb of the noncontracting muscle. Thus it is concluded that the centrally induced vasodilator signal is equally transmitted to the bilateral VL muscles, not only during imagery of exercise but also at the start period of voluntary exercise in humans.