scholarly journals The initiation of phasic and tonic contraction by potassium and the effect of calcium,Multivalent cations and Ca-antagonist on potassium contracture in guinea-pig vas deferens.

1981 ◽  
Vol 31 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Mitsuhiro SHIMODAN ◽  
Satoru SUNANO
Keyword(s):  
Guinea Pig ◽  
Vas Deferens ◽  
Tonic Contraction ◽  
Potassium Contracture ◽  
Ca Antagonist ◽  
Phasic And Tonic Contraction

Discrimination by nimodipine, but not by nifedipine, between phasic and tonic contractions of guinea-pig taenia coli induced by K+ depolarization

1995 ◽  
Vol 73 (11) ◽  
pp. 1600-1604 ◽  
Author(s):  
Sadaharu Usune ◽  
Takeshi Katsuragi ◽  
Tatsuo Furukawa
Keyword(s):  
Guinea Pig ◽  
Tonic Contraction ◽  
Channel Blockers ◽  
Dependent Manner ◽  
Taenia Coli ◽  
Concentration Dependent Manner ◽  
Phasic Contraction ◽  
High K ◽  
Phasic And Tonic Contraction ◽  
Longitudinal Muscles

Effects of Ca2+ channel blockers, such as nifedipine, nimodipine, gallopamil, verapamil, diltiazem, loperamide, Mn2+ and Ni2+, and papaverine, on contractile responses to K+ depolarization were evaluated in longitudinal muscles of taenia coli isolated from guinea-pig. Depolarization with high K+ solution (K+, 40 mM) produced a biphasic (phasic and tonic) contraction, which was inhibited by the above blockers in a concentration-dependent manner. Ratios of IC50 for the phasic contraction to IC50 for the tonic contraction of nimodipine, verapamil, gallopamil, nifedipine, loperamide, diltiazem, papaverine, Ni2+, and Mn2+ were 516.1, 73.7, 22.0, 6.4, 5.3, 4.9, 1.2, 0.7, and 0.1, respectively, indicating that nimodipine suppressed the tonic contraction more effectively than the phasic contraction. In a fluorescence study with fura 2, K+ depolarization elicited an increase in intracellular free Ca2+, [Ca2+]i, which was coupled with the phasic and tonic contraction. The increases in [Ca2+]i coupled with both types of the contraction were abolished by exposure to Ca2+-free solution. In addition, the increase of [Ca2+]i coupled with the phasic contraction was abolished by nifedipine, 10−7 M, but not by nimodipine, 10−7 M, whereas the increase with the tonic contraction was suppressed by both nifedipine and nimodipine. These findings suggest that the phasic and tonic contractions evoked by K+ depolarization are due to increases in [Ca2+]i via activation of respective nimodipine-resistant and nimodipine-sensitive Ca2+ channels in the longitudinal muscles of the taenia coli. Accordingly, nimodipine, but not nifedipine, appears to be a useful tool for distinguishing between the phasic and tonic contractions.Key words: guinea-pig taenia coli, phasic contraction, tonic contraction, nimodipine, nifedipine, intracellular free Ca2+.

Contribution of Na+ and membrane depolarization to contraction induced by adrenaline in the guinea pig vas deferens

1986 ◽  
Vol 64 (6) ◽  
pp. 720-723 ◽  
Author(s):  
Sadaharu Usune ◽  
Takeshi Katsuragi ◽  
Yasuzi Sakamoto ◽  
Tatsuo Furukawa
Keyword(s):  
Guinea Pig ◽  
Vas Deferens ◽  
Rhythmic Activity ◽  
Membrane Depolarization ◽  
Tonic Contraction ◽  
Rhythmic Contraction ◽  
High K ◽  
Membrane Bound ◽  
Small Contraction ◽  
Rhythmic Contractions

The contribution of Na+ and membrane depolarization to biphasic contractions induced by adrenaline were investigated in the smooth muscle of guinea pig vas deferens. Adrenaline (5 × 10−6 M) produced an initial small contraction (first contraction) followed by a large tonic contraction (second contraction) with subsequent rhythmic activity. The entire response to adrenaline was largely inhibited by phentolamine (5 × 10−6 M). By adding an appropriate concentration of Mn2+ (2 × 10−4 M) or nifedipine (3 × 10−7 M), a Ca2+ blocker, the second contraction was strongly reduced, accompanied by abolishment of the rhythmic contraction, whereas the first contraction was virtually unaffected. However, the first contraction was markedly suppressed by a higher concentration of Mn2+. All contractions produced by adrenaline were greatly reduced in Ca2+-free solution containing 0.5 mM EGTA. By lowering external Na+ concentration, the first contraction was markedly increased without greatly affecting the second contraction. By exposure to Na+-free isotonic high K+ solution, which elicited a greater depolarization of the membrane, the first contraction produced by adrenaline was also greatly potentiated, while the second and rhythmic contractions were eliminated. These results suggest that the adrenaline-evoked first contraction may be due to an influx of membrane bound Ca2+ which is independent of membrane depolarization, while the second (rhythmic) contraction is due to an influx of extracellular Ca2+ which is dependent upon depolarization.

Ca45 uptake and tissue calcium in K-induced phasic and tonic contraction in taenia coli

1964 ◽  
Vol 207 (4) ◽  
pp. 873-876 ◽  
Author(s):  
N. Urakawa ◽  
W. C. Holland
Keyword(s):  
Guinea Pig ◽  
Muscle Contraction ◽  
Significant Rise ◽  
Tonic Contraction ◽  
Taenia Coli ◽  
Free Medium ◽  
Phasic Contraction ◽  
High K ◽  
Tissue Calcium ◽  
Phasic And Tonic Contraction

High-K medium produces a tonic contraction in guinea pig taenia coli. If muscle strips are preincubated in glucose-free medium, K produces only a phasic contraction. A comparison of Ca45 entry and tissue Ca changes in the two responses were made. Both responses are accompanied by an enhanced uptake of Ca45. In addition to an increased Ca45 uptake, a significant rise of tissue Ca was observed during the tonic contraction. No detectable changes in tissue Ca were noted in the phasic contraction. In light of modern theories of muscle contraction, it was proposed that in the phasic contraction, sufficient Ca is released from a cellular site to initiate contraction, whereas in the tonic contraction enough Ca crosses the membrane to initiate contraction. The transmembrane Ca transport involved in the latter response appeared to be dependent on metabolism.

scholarly journals Inhibitory effect of beauvericin on a high K+-induced tonic contraction in guinea-pig taenia coli.

1987 ◽  
Vol 45 (3) ◽  
pp. 317-325 ◽  
Author(s):  
Shinjiro NAKAJYO ◽  
Kiyomi MATSUOKA ◽  
Tomohiro KITAYAMA ◽  
Yutaka YAMAMURA ◽  
Kazumasa SHIMIZU ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Inhibitory Effect ◽  
Tonic Contraction ◽  
Taenia Coli ◽  
High K

Opioid agonist affinity in the guinea-pig ileum and mouse vas deferens

1990 ◽  
Vol 179 (1-2) ◽  
pp. 129-139 ◽  
Author(s):  
Frank Porreca ◽  
Diane LoPresti ◽  
Susan J. Ward
Keyword(s):  
Guinea Pig ◽  
Vas Deferens ◽  
Guinea Pig Ileum ◽  
Opioid Agonist ◽  
Mouse Vas Deferens ◽  
Agonist Affinity
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