Determination of local catecholamine release by microdialysis.
Release of noradrenaline in subcutaneous tissue was measured using a microdialysis technique in combination with an ultrasensitive radio-enzymatic noradrenaline assay. Experiments were performed in conscious dogs with and without tyramine added to the perfusion medium. In the absence of tyramine, the interstitial noradrenaline levels in subcutaneous tissue were similar to arterial blood concentrations provided the former were corrected for recovery. With tyramine added to the perfusion medium, noradrenaline levels in subcutaneous tissue increased tenfold. Arterial noradrenaline concentrations did not change, indicating that noradrenaline was released only locally in the tissue. In four healthy males, the subcutaneous dialysate noradrenaline concentration increased during cold exposure by a factor of 3.5 (Friedman test, P < 0.003). Skin temperature decreased by an average of -12 degrees C +/- 0.6 degrees C during cold exposure. The microdialysis technique in combination with a sensitive radio-enzymatic noradrenaline assay may be useful to assess local subcutaneous noradrenaline release.
Grønlund
B
B
Department of Internal Medicine and Endocrinology, Herlev University Hospital, Denmark.
Grønlund
L
L
Astrup
A
A
Bie
P
P
Christensen
N J
NJ
D000328:Adult; D000818:Animals; D003080:Cold Temperature; D003956:Dialysis / Q000379:methods*; D004285:Dogs; D005260:Female; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*
D009638:Norepinephrine