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Effects of polyamines on intracellular calcium and mechanical activity in smooth muscle of guinea-pig taenia coli

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Author

Summary, in English

The effects of the polyamines putrescine, spermidine and spermine on the mechanical activity in smooth muscle from guinea-pig taenia coli were investigated. Tissue concentrations of spermidine and spermine were about 240 and 160 nmol g-1, respectively, while the putrescine concentration was much lower (4 nmol g-1). Intracellular [Ca2+] was determined using the Fura-2 method and the effects of extracellularly applied polyamines were observed. Spermine (10(-5)-10(-3) mol l-1) dose-dependently inhibited spontaneous contractions as well as contractions induced by 20-25 mmol l-1 KCl, with 10(-3) mol l-1 spermine giving nearly total relaxation. Spermidine (10(-3) mol l-1) relaxed a 20 mmol l-1 KCl contracture, while putrescine had no effect. A decrease in intracellular [Ca2+] accompanied the relaxation induced by spermine. In contrast to the effects on spontaneous activity and intermediate [KCl], both the contraction and the accompanying increase in intracellular [Ca2+] induced by 90-120 mmol l-1 KCl were unaffected by spermine. Spermine did not affect the maximal Ca(2+)-induced force of chemically skinned taenia coli preparations, but a small potentiating effect on the Ca2+ sensitivity was observed. The results indicate that the relaxation induced by spermine depends on an intact cell membrane. Furthermore, the relaxing effect is due to decreased intracellular [Ca2+] and seems to occur only when the contraction is elicited by repetitive action potentials, and not by sustained depolarization.

Publishing year

1993

Language

English

Pages

37-43

Publication/Series

Acta Physiologica Scandinavica

Volume

148

Issue

1

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Physiology

Status

Published

Research group

  • Vascular Physiology

ISBN/ISSN/Other

  • ISSN: 0001-6772