Vol. 273, Issue 6, H2850-H2856, December 1997
Use of microdialysis for monitoring sympathetic and
parasympathetic innervation of heart in conscious rats
T. I. F. H.
Cremers1,
A. C. H.
Teisman2,
W. H.
Van
Gilst2, and
B. H. C.
Westerink1
1 Department of Medicinal
Chemistry, University Centre for Pharmacy, and
2 Department of Clinical
Pharmacology, Faculty of Medicine, University of Groningen, 9713 AV
Groningen, The Netherlands
A microdialysis method was developed to sample
norepinephrine and acetylcholine from the heart of freely moving rats.
A flexible dialysis fiber (length 14 mm), with a copper wire inserted
inside, was implanted into the heart. Extracellular norepinephrine was detectable for at least 72 h after implantation. Basal output levels 24 h after surgery were 140 pg/ml when corrected for in vitro recovery.
Evidence was provided that the major part of norepinephrine in
dialysates is derived from local neurotransmission. Acetylcholine was
only detectable in cardiac dialysates when an esterase inhibitor was
infused. Corrected basal output levels 24 h after surgery were 223 pg/ml when neostigmine was coinfused in a concentration of 100 µmol/l. In addition, the presence of local muscarinic autoreceptors on cholinergic neurons in the heart was shown. It is concluded that
microdialysis is a reliable method that can be used to study the
innervation of the heart in subchronic preparations in freely moving
rats.
muscarinic receptors; neurotransmission
