Intravenous adrenaline infusion causes vasoconstriction close to an intramuscular microdialysis catheter in humans.
OBJECTIVE
To test if a small muscle injury influences the vascular reactivity to adrenaline in human skeletal muscle.


METHODS
Blood flow was measured by ¹³³Xenon clearance in the gastrocnemius muscle of eight male subjects at basal and during i.v. infusion of adrenaline (0.1 nmol kg⁻¹ min⁻¹) or placebo. Measurements were done with (expts 2 and 3) or without (expt 1) the influence of a small muscle injury induced by inserting a microdialysis catheter. ¹³³Xenon was administered either (expt 1) conventionally into the muscle via a fine needle, or (expts 2 and 3) through a fine tube close to the inserted microdialysis catheter. Expt 3 (control expt) was identical to expt 2 except that placebo was infused instead of adrenaline. Mean ± SEM, n= 8.


RESULTS
The blood flow tended to increase during the adrenaline infusion in expt 1 (1.17 ± 0.10 to 1.39 ± 0.15, N.S.), whereas it decreased during the adrenaline infusion in expt 2, from 1.39 ± 0.14 to 1.03 ± 0.14 ml min⁻¹ 100 g tissue⁻¹ (P<0.001). The blood flow change in response to adrenaline infusion was significantly different in expt 1 and expt 2 (P<0.05). Blood flow also decreased during the placebo infusion in expt 3 (1.15 ± 0.10 to 1.00 ± 0.09, P<0.01), but this decrease was significantly smaller than in response to the adrenaline infusion in expt 2, P<0.01.


CONCLUSIONS
The present results are consistent with the hypothesis that the small muscle injury caused by the inserted microdialysis catheter influences the vascular reactivity to adrenaline in a vasoconstrictive direction.
Vedung
Torbjörn
T
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Jorfeldt
Lennart
L
Henriksson
Jan
J
D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002408:Catheters, Indwelling / Q000009:adverse effects; D004837:Epinephrine / Q000008:administration & dosage*; D006339:Heart Rate; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D017551:Microdialysis / Q000009:adverse effects / Q000295:instrumentation*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000293:injuries; D012039:Regional Blood Flow; D013548:Sweden; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*; D014980:Xenon Radioisotopes / Q000008:administration & dosage; D055815:Young Adult
D014662:Vasoconstrictor Agents; D014980:Xenon Radioisotopes; D004837:Epinephrine