Presynaptic beta-adrenoceptors in guinea pig papillary muscle: evidence for adrenaline-mediated positive feedback on noradrenergic transmission

Journal Article · Fri Feb 01 04:00:00 EST 1991 · Journal of Cardiovascular Pharmacology; (USA)

OSTI ID:5761234

Valenta, B; Singer, E A ^[1]

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1. Univ. of Vienna, (Austria)

Guinea pig papillary muscles were preincubated in the presence of 5 x 10{sup {minus} 9} mol/L unlabeled noradrenaline or adrenaline then incubated with ({sup 3}H)-noradrenaline and superfused. Electrical field stimulation with 180 pulses delivered at 1 or 3 Hz was used to induce overflow of radioactivity. Comparison of the effects of preexposure of the tissue to adrenaline or noradrenaline revealed that adrenaline incubation caused an enhancement of stimulation-evoked overflow of ({sup 3}H)noradrenaline and a reduction of the effect of exogenously added isoprenaline. Furthermore, the selective beta 2-adrenoceptor antagonist ICI 118,551 (10{sup {minus} 7} mol/L), but not the selective beta 1-adrenoceptor antagonist ICI 89,406 (10{sup {minus} 7} mol/L), reduced electrically evoked overflow of ({sup 3}H)noradrenaline in tissue preincubated with adrenaline but not in tissue preincubated with noradrenaline. The overflow-reducing effect of ICI 118.551 occurred at stimulation with 3 Hz but not at stimulation with 1 Hz. The present results support the hypothesis that noradrenergic transmission in guinea pig papillary muscle is facilitated via beta 2-adrenoceptors, and that adrenaline may serve as transmitter in this positive feedback mechanism after its incorporation into sympathetic nerves.

• OSTI ID: 5761234
• Journal Information: Journal of Cardiovascular Pharmacology; (USA), Journal Name: Journal of Cardiovascular Pharmacology; (USA) Vol. 17:2; ISSN 0160-2246; ISSN JCPCD
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ADRENALINE
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
CARDIOTONICS
CARDIOVASCULAR AGENTS
DRUGS
ELECTROPHYSIOLOGY
FEEDBACK
GUINEA PIGS
HORMONES
HYDROGEN COMPOUNDS
IN VITRO
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
MEMBRANE PROTEINS
MUSCLES
NERVES
NERVOUS SYSTEM
NEUROREGULATORS
NORADRENALINE
ORGANIC COMPOUNDS
PHYSIOLOGY
PROTEINS
REACTION KINETICS
RECEPTORS
RODENTS
SYMPATHOMIMETICS
SYNTHESIS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES