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Effects of divalent cations and La 3+ on contractility and ecto‐ATPase activity in the guinea‐pig urinary bladder
Author(s) -
Ziganshin Airat U.,
Ziganshina Lilia E.,
Hoyle Charles H.V.,
Burnstock Geoffrey
Publication year - 1995
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1995.tb17186.x
Subject(s) - chemistry , carbachol , stimulation , divalent , contractility , endocrinology , medicine , atpase , guinea pig , biophysics , biochemistry , biology , enzyme , organic chemistry
1 Several cations (Ba 2+ , Cd 2+ , Co 2+ , Cu 2+ , Mn 2+ , Ni 2+ , Zn 2+ and La 3+ , all as chloride salts, 1–1000 μ m ) were tested in the guinea‐pig urinary bladder for their ability to: (i) modify contractile responses to electrical field stimulation (EFS), ATP, α,β‐methylene ATP (α,β‐meATP), carbachol (CCh), and KCl; (ii) affect ecto‐ATPase activity. 2 Ba 2+ (10–1000 μ m ) concentration‐dependently potentiated contractile responses evoked by EFS (4–16 Hz), ATP (100 μ m ), α,β‐meATP (1 μ m ), CCh (0.5 μ m ), and KCl (30 m m ). Ni 2+ at concentrations of 1–100 μ m also potentiated contractility of the urinary bladder, but at concentrations tested its effect was not concentration‐dependent. Cu 2+ at a concentration of 10 μ m and Cd 2+ at a concentration of 1 μ m potentiated responses to all stimuli, except KCl. Ni 2+ at a concentration of 1000 μ m and Cd 2+ at a concentration of 100 μ m inhibited contractions evoked by all stimuli, and at a concentration of 1000 μ m Cd 2+ abolished any contractions. Responses to ATP and α,β‐meATP were selectively inhibited by Cu 2+ , Zn 2+ or La 3+ , each at a concentration of 1 m m . 3 Cu 2+ , Ni 2+ , Zn 2+ and La 3+ (100–1000 μ m ) concentration‐dependently inhibited ecto‐ATPase activity in the urinary bladder smooth muscle preparations, while Ba 2+ and Mn 2+ were without effect, and Cd 2+ and Co 2+ caused significant inhibition only at a concentration of 1000 μ m . 4 There was no correlation between the extent of ecto‐ATPase inhibition and the effect on contractile activity of any of the cations. 5 In conclusion, the ability of some divalent cations to inhibit ecto‐ATPase activity and to potentiate or inhibit contractile responses in the guinea‐pig urinary bladder appear to be independent effects.