We have studied the effects of handgrip on plasma levels of catecholamines, neuropeptide Y (NPY), and leu-enkephalin before and after hemodialysis of uremic patients. A cuprophan dialyzer was used. We found, that dopamine level was higher in uremia group before hemodialysis both during rest (0.38 +/- 0.39 pmol/ml) and handgrip (1.13 +/- 1.00 pmol/ml) compared to control (0.17 +/- 0.19, and 0.66 +/- 0.83 pmol/ml respectively). Hemodialysis leads to further increase of its level (0.49 +/- 0.35 pmol/ml) at rest. Epinephrine level was almost the same in uremic patients before (0.43 +/- 0.51 pmol/ml) and after dialysis (0.46 +/- 0.60) as in control subjects (0.41 +/- 0.37 pmol/ml) during the rest. Its level measured after the handgrip was the highest in uremic group after dialysis (2.10 +/- 2.00 pmol/ml), significantly lower before dialysis (1.26 +/- 0.85 pmol/ml), and the lowest in control group (0.78 +/- 0.43 pmol/ml). Norepinephrine level were very similar in uremic group before dialysis (1.54 +/- 1.05 pmol/ml), after dialysis (1.79 +/- 1.29 pmol/ml) and in control group (1.46 +/- 1.06 pmol/ml) during the rest. During the handgrip test its level was higher in uremic group after hemodialysis than before it (adequate values 8.78 +/- 4.61 and 6.70 +/- 4.74 pmol/ml). The difference between uremia group before dialysis and control group did not reach significance. The level of NPY has the tendency to increase in uremic patients. Dialysis leads to following increase of its level, but the changes did not reach the significance both in rest and handgrip. Leu-enkephalin level was higher in uremic group (9.21 +/- 7.62 pmol/ml) compared to control (5.22 +/- 1.53 pmol/ml). We observed non-significant fall of this level after dialysis (6.79 +/- 4.76 pmol/ml). We found the same tendency during the handgrip, and the changes were significant.
In conclusion: uremia per se leads to increase the level of dopamine and leu-enkephaline during the rest and handgrip, but the level of epinephrine only during the handgrip; dialysis leads to further increase of dopamine during the rest, but epinephrine, norepinephrine and leu-enkephaline only during the handgrip.