Norepinephrine uptake by rat jejunum: Modulation by angiotensin II
- CIBA-GEIGY Corp., Summit, NJ (USA)
Angiotensin II (ANG II) is believed to stimulate sodium and water absorption from the small intestine by enhancing sympathetic nerve transmission. This study is designed to determine whether ANG II can enhance sympathetic neurotransmission within the small intestine by inhibition norepinephrine (NE) uptake. Intracellular NE accumulation by rat jejunum was concentration dependent and resolved into high- and low-affinity components. The high-affinity component (uptake 1) exhibited a Michaelis constant (K{sub m}) of 1.72 {mu}M and a maximum velocity (V{sub max}) of 1.19 nmol {center dot} g{sup {minus}1} {center dot} 10 min{sup {minus}1}. The low-affinity component (uptake 2) exhibited a K{sub m} of 111.1 {mu}M and a V{sub max} of 37.1 nmol {center dot} g{sup {minus}1} {center dot} 10 min{sup {minus}1}. Cocaine, an inhibitor of neuronal uptake, inhibited the intracellular accumulation of label by 80%. Treatment of animals with 6-hydroxydopamine, which depletes norepinephrine from sympathetic terminals, also attenuated NE uptake by 60%. Thus accumulation within sympathetic nerves constitutes the major form of ({sup 3}H)NE uptake into rat jejunum. ANG II inhibited intracellular ({sup 3}H)NE uptake in a concentration-dependent manner. At a dose of 1 mM, ANG II inhibited intracellular ({sup 3}H)NE accumulation by 60%. Cocaine failed to potentiate the inhibition of ({sup 3}H)NE uptake produced by ANG II. Thus ANG II appears to prevent ({sup 3}H)NE accumulation within rat jejunum by inhibiting neuronal uptake.
- OSTI ID:
- 6868172
- Journal Information:
- American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 254:2; ISSN 0002-9513; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ABSORPTION
ADRENAL HORMONES
ADRENALINE
ALKALOIDS
ANESTHETICS
ANGIOTENSIN
ANIMALS
ANTIDEPRESSANTS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BIOELECTRICITY
BIOLOGICAL EFFECTS
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
CENTRAL NERVOUS SYSTEM AGENTS
CENTRAL NERVOUS SYSTEM DEPRESSANTS
COCAINE
DIGESTIVE SYSTEM
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ELECTRICITY
GASTROINTESTINAL TRACT
GLOBULINS
HYDROGEN COMPOUNDS
INTESTINAL ABSORPTION
INTESTINES
KINETICS
MAMMALS
NERVES
NERVOUS SYSTEM
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
PSYCHOTROPIC DRUGS
RATS
REACTION KINETICS
RODENTS
SMALL INTESTINE
SYMPATHOMIMETICS
TRITIUM COMPOUNDS
UPTAKE
VASOCONSTRICTORS
VERTEBRATES