Lack of presynaptic modulation by isoprenaline of 3H-noradrenaline release from rabbit isolated ear artery |
| |
Authors: | Jan Abrahamsen Ove A. Nedergaard |
| |
Affiliation: | (1) Department of Pharmacology, School of Medicine, Odense University, J. B. Winsløws Vej 19, DK-5000 Odense C, Denmark |
| |
Abstract: | Summary The aim of the present investigation was to examine whether or not presynaptic facilitatory -adrenoceptors are detectable on the postganglionic nerves in the rabbit isolated ear artery. Strips of rabbit central ear artery were incubated with 3H-noradrenaline (10–7 mol/l; 30 min or 10–6 mol/l; 60 min). Subsequently, they were washed repeatedly with physiological salt solution. The strips were subjected to electrical-field stimulation (S1–S8) and the resultant 3H-overflow was determined.When the ear artery was stimulated with 150 pulses (0.5 ms; 3 Hz; 225 mA), isoprenaline (10–9–10–6 mol/l) either alone or in the presence of either rauwolscine (10–6 mol/l) or phentolamine (10–6 mol/l) did not alter the stimulation-evoked 3H-overflow. This was also the case in the presence of rauwolscine (10–6 mol/l) plus either the selective phosphodiesterase inhibitor ICI 63 197 (3 × 10–5 mol/l) or forskolin (10–6 mol/l). When the ear artery was stimulated with 300 pulses (1 ms; 5 Hz; 225 mA), isoprenaline had no effect on the stimulation-evoked 3H-overflow. This was also the case when phentolamine (10–6 mol/l) was present. Propranolol (10–7–10–5 mol/l) did not alter the stimulation-evoked 3H-overflow. In some experiments, the stimulation current was reduced to 175 mA in order to obtain similar reference release (S3) values despite the presence of rauwolscine (150 pulses; 0.5 ms; 3 Hz). Even then, isoprenaline (10–9–10–6 mol/l) did not change stimulation-evoked 3H-overflow. The results suggest that postganglionic sympathetic nerves in rabbit central ear artery do not possess presynaptic facilitatory -adrenoceptors.Send offprint requests to J. Abrahamsen at the above address |
| |
Keywords: | 3H-Noradrenaline release Rabbit ear artery Presynaptic /content/jq88r0j57h125649/xxlarge946.gif" alt=" beta" align=" MIDDLE" BORDER=" 0" >-adrenoceptors Isoprenaline Forskolin |
本文献已被 SpringerLink 等数据库收录! |
|