Pressor responses during static handgrip exercise in paraplegics
Fumihiro Tajima, H. Ogata, H. Okawa, M. Abe, T. Mizushima, and K.H. Lee.
(University of Occupational and Environmental Health, Kitakyushu, Japan)
We studied heart rate (HR), mean blood pressure (MBP), and skin blood flow (SkBF) of the paralyzed area (leg) in 5 normal and 5 complete traumatic spinal cord transected paraplegic subjects (T5-T12 lesion). After 2 rain of rest in supine position (control), each subject performed the static hand grip exercise at 35% of their maximum voluntary contraction for 2.5 min, and then 4 min of recovery period was observed. HR in normal and paraplegics increased significantly (P<0.05) from 67.02.6 and 65.0±1.6 during control to 81.9±8.6 and 77.1±1.7 beats/rain during exercise respectively, and HR in either group immediately recovered to control values after exercise. MBP in normal (90.0±2.0 mmHg) and paraplegics (89.6±5.0 mmHg) increased significantly (P<0.05) to 117±5 and 116±7 mmHg during exercise respectively. SkBF of leg in normal and paraplegics increased (P<0.05) by 46±7 and 82±37% during exercise respectively. The increase of SkBF in paraplegics were greater (P<0.05) than normal from 45 sec to the end of the exercise. Cutaneous vascular conductance (CVC), calculated in SkBF divided by MBP, did not significantly change in normal subjects, however CVC in paraplegics significantly (P<0.05) increased by 43±24% during exercise. The increased HR suggest that the cardiac response to static exercise in paraplegics is similar to normal, however the increased CVC in paraplegics during static exercise suggests that paraplegics might have different circulatory system in peripheral vessels from normals. It is concluded that the isolation of the peripheral nerve in the leg from spinal cord injury alters SkBF below the lesion in paraplegics much more significantly.
EXPERIMENTAL AND CLINICAL STUDIES OF EICOSANOIDS IN CEREBROSPINAL FLUID AFTER SPINAL CORD INJURY
T. Tonai, T. Nishisho, Y. Tamura, and T. Ikata* (Zentsuji National Hospital, Zentsuji, and Tokushima University*, Tokushima, Japan)
Abstract: In an attempt to elucidate a possible role of eicosanoids in the pathogenesis of spinal cord injury (SCI), we measured the concentration of leukotriene (LT) C4, thromboxane (TX) B2 and 6-keto-prostaglandin (PG) F1α in cerebrospinal fluid (CSF) in both a canine experimental model and 11 SCI patients.
The eicosanoid concentration in CSF was measured by radioimmunoassay. Neurological severity was assessed according to the grading system of Frankel. Control samples were obtained from 20 patients without spinal cord lesion.
In the canine model, a significant increase in all eicosanoids was found on days 1-7, which subsequently returned to the control level. In the clinical study, the highest mean (± standard error) concentrations of LTC4, TXB2, and 6-keto-PGF1α in the acute stage of SCI were 95.9±10.7 pg/ml, 175.2±38.2 and 167.5±39.9 pg/ml, respectively. These concentrations were 5-9 times higher than control levels. There was a good correlation between CSF LTC4 levels and the neurological severity. The time-dependent change in LTC4 concentrations in 7 SCI patients was similar to that observed in the canine model. In addition, the highest mean concentrations of the eicosanoids measured in patients with complete paralysis was also similar to those of the canine model. The eicosanoids concentrations in 5 SCI patients were repeated to measure more than 6 months after the onset of injury. Although all eicosanoids levels had elevated in the acute stage of injury, they were not elevated and showed the same levels as the controls at the chronic stage.
These findings suggest that enhanced arachidonate metabolism does occur in humans and supports the evidence from animal experiments that emphasizes the importance of eicosanoids in the second processes mediating ischemia and edema.