TY - JOUR
T1 - Effects of polyamines on intracellular calcium and mechanical activity in smooth muscle of guinea-pig taenia coli
AU - Nilsson, Bengt-Olof
AU - Hellstrand, Per
PY - 1993
Y1 - 1993
N2 - 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.
AB - 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.
U2 - 10.1111/j.1748-1716.1993.tb09529.x
DO - 10.1111/j.1748-1716.1993.tb09529.x
M3 - Article
C2 - 8333295
SN - 0001-6772
VL - 148
SP - 37
EP - 43
JO - Acta Physiologica Scandinavica
JF - Acta Physiologica Scandinavica
IS - 1
ER -