Inorganic phosphate inhibits sympathetic neurotransmission in canine saphenous veins
Inorganic phosphate has been proposed as the initiator of metabolic vasodilatation in active skeletal muscle. The present study was primarily designed to determine if this substance has an inhibitory effect on adrenergic neurotransmission. Rings of canine saphenous veins were suspended for isometric tension recording in organ chambers. A comparison was made of the ability of inorganic phosphate (3 to 14 mM) to relax rings contracted to the same degree by electrical stimulation, exogenous norepinephrine, and prostaglandin F/sub 2..cap alpha../. The relaxation during electrical stimulation was significantly greater at all concentrations of phosphate. In strips of saphenous veins previously incubated with (/sup 3/H)norepinephrine, the depression of the contractile response caused by phosphate during electrical stimulated was accompanied by a significant reduction in the overflow of labeled neurotransmitter. Thus inorganic phosphate inhibits sympathetic neurotransmission and hence may have a key role in the sympatholysis in the active skeletal muscles during exercise. By contrast, in this preparation, it has a modest direct relaxing action on the vascular smooth muscle.
- Research Organization:
- Mayo Medical School, Rochester, MN
- OSTI ID:
- 6409598
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 252:1; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMISTRY
BIOELECTRICITY
BLOOD VESSELS
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
CHEMISTRY
DOGS
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ELECTRICITY
HORMONES
INHIBITION
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MUSCLES
NERVES
NERVOUS SYSTEM
NEUROREGULATORS
NORADRENALINE
ORGANS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PROSTAGLANDINS
STEROID HORMONES
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VEINS
VERTEBRATES