Increased reactivity of venous smooth muscle by small decreases in extracellular sodium
| Autor: | R. R. Lorenz, O. Beaty, J. T. Shepherd |
|---|---|
| Rok vydání: | 1978 |
| Předmět: |
medicine.medical_specialty
Physiology Sodium chemistry.chemical_element Adrenergic Stimulation Calcium In Vitro Techniques Veins Norepinephrine (medication) Norepinephrine Dogs Physiology (medical) Internal medicine medicine Extracellular Animals Muscle Smooth Acetylcholine Electric Stimulation Endocrinology chemistry Verapamil Barium Cardiology and Cardiovascular Medicine Extracellular Space medicine.drug Muscle Contraction |
| Zdroj: | The American journal of physiology. 235(5) |
| ISSN: | 0002-9513 |
| Popis: | In dog saphenous vein strips, decreases in extracellular sodium from 5% to 23% did not alter basal tension, but progressively increased tension developed during electrical stimulation (1.0 to 10 Hz). The augmentation did not occur with similar reductions in chloride ions. When osmolality was maintained with sucrose, the response to electrical stimulation also was enhanced with a 5% reduction in sodium ions, but did not increase further with larger sodium reductions. The enhancement was due to some effect on the smooth muscle cells, because the overflow of [7-3H]norepinephrine during electrical stimulation was unaffected by the sodium reduction, whereas contractions caused by norepinephrine and barium chloride were potentiated. The potentiation did not depend on increased influx of extracellular calcium, because contractions induced by acetylcholine were unaffected by sodium reduction; and after blocking calcium influx with verapamil, the norepinephrine contractions still were augmented. It was concluded that a decrease in extracellular sodium by 5% (from the normal value of 143.3--131.1 meq/1) can enhance the response of venous smooth muscle to adrenergic stimuli. |
| Databáze: | OpenAIRE |
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