• The Korean Journal of Pharmacology
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• v.26 no.2
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• pp.113-120
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• 1990

Influences of trigger calcium on myocardial contraction from several sources were investigated on the frequency reduction-induced changes of contraction in rat left atria driven by electrical field stimulation. Rat atria elicited characteristic three phase-changes according to frequency reduction: the first rapid rise in twitch tension, the second transient fast decrease in tension and the third maintenance of twitch tension at about 200% of resting tension during high frequency. Caffeine treatment enormously suppressed the frequency reduction-induced twitch tension increase. The atrial contraction during high frequency vanished after verapamil treatment. But, during low frequency, atrial contraction revived in the presence of verapamil. Ouabain treatment and sodium depletion in superfusing solution abolished the characteristic second phase with slow frequency. These results suggest that slow calcium channel is an indispensable calcium entry route and calcium release from sarcoplasmic reticulum is an major source for trigger calcium in cardiac contraction. And sodium-calcium exchange has a modulatory roles in the regualtion of trigger calcium according to the changes of intracellular sodium concentration.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.3
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• pp.189-194
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• 2009

This study was designed to clarify the mechanism of the inhibitory effect of forskolin on contraction, cytosolic $Ca^{2+}$ level $([Ca^{2+}]_i)$, and $Ca^{2+}$ sensitivity in guinea pig ileum. Forskolin (0.1 nM ${\sim}$ 10 ${\mu}M$) inhibited high $K^+$ (25 mM and 40 mM)- or histamine (3 ${\mu}M$)-evoked contractions in a concentration-dependent manner. Histamine-evoked contractions were more sensitive to forskolin than high $K^+$-evoked contractions. Spontaneous changes in $[Ca^{2+}]_i$ and contractions were inhibited by forskolin (1 ${\mu}M$) without changing the resting $[Ca^{2+}]_i$. Forskoln (10 ${\mu}M$ ) inhibited muscle tension more strongly than $[Ca^{2+}]_i$ stimulated by high $K^+$, and thus shifted the $[Ca^{2+}]_i$-tension relationship to the lower-right. In histamine-stimulated contractions, forskolin (1 ${\mu}M$) inhibited both $[Ca^{2+}]_i$ and muscle tension without changing the $[Ca^{2+}]_i$-tension relationship. In ${\alpha}$-toxin-permeabilized tissues, forskolin (10 ${\mu}M$) inhibited the 0.3 ${\mu}M$ $Ca^{2+}$-evoked contractions in the presence of 0.1 mM GTP, but showed no effect on the $Ca^{2+}$-tension relationship. We conclude that forskolin inhibits smooth muscle contractions by the following two mechanisms: a decrease in $Ca^{2+}$ sensitivity of contractile elements in high $K^+$-stimulated muscle and a decrease in $[Ca^{2+}]_i$ in histamine-stimulated muscle.

• Journal of the Korean Applied Science and Technology
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• v.21 no.2
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• pp.182-189
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• 2004

On contraction of the muscles, marked changes in X-ray reflections are observed, suggesting that conformational changes of contractile molecules and the movement of myosin heads during muscle contraction. Time slice requires tension peak after the onset of stimulation and the height of tension peak depends on the number of twitch cycle. The muscles were stimulated by five successive stimuli at an interval of 80 ms started while the tension was still being exerted by the muscles. The intensity of $I_{11}$, $I_{10}$, $143{\AA}$ and $215{\AA}$ reflection measured with 5ms time resolution and is recorded in isometric tension. The peak height of $I_{11}$ and $143{\AA}$ intensity is changed after the onset of a stimulation $I_i$, and the length of twitch is shortened by successive twitches in the case of stimulation $T_i$. On the other hand, the peak height of In and $215{\AA}$ intensity starts to decrease at the 1st twitch and remains constant at low peak height without appreciable recovery during the contraction term. In the case of successive twitch stimulation, the myosin heads of muscle are once moved from their resting position and never returned to their initial position.

• The Korean Journal of Physiology
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• v.16 no.1
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• pp.13-23
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• 1982

Effects of external pH and potassium concentrations on the electrical and mechanical properties were investigated on rabbit papillary muscle. Papillary muscles were perfused in horizontal chamber with Tris Tyrode solutions and action potential along with isometric tension was recorded simultaneously. Potassium concentrations were varied between 1 and 12 mM at low(6.9), normal(7.4) and high (7.9) external pH. The following results were obtained: 1) On rasing the potassium concentration from 1 to 12 mM resting membrane potentials decreased from $-88.8{\pm}2.8$ to $-66.4{\pm}1.2\;mV$ at normal pH and the amplitude of action potential decreased from $115.1{\pm}0.7$ to $97.5{\pm}2.8\;mV$. On lowering the potassium concentration, membrane hyperpolarized and at 1 mM potassium concentration resting potentials were $-107{\pm}2.2\;mV$. Duration of action potential especially $APD_{60}{\sim}APD_{90}$ increased($APD_{90}$: $214{\pm}15.8\;ms$ at 1 mM $K^+$ to $287{\pm}18.1\;ms$ at 12 mM $K^+$). 2) During acidosis membranes hyperpolarized by more than 20 mV within 1 min. and then slow recovery was observed during the following 10 min. During alkalosis membranes depolarized about 10 mV, which were maintained until washing with normal Tyrode solutions. 3) On lowering the external pH(7.9-6.5), duration of action potential increased progressively and it was most prominent at pH 6.5 and $K^+$ 1mM. 4) Magnitude of developed tension was $0.6{\pm}0.14\;g/mm^2$ at normal pH and potassium concentration (stimulus frequency : 60/min). Relative isometric tension to normal value increased along the increment of stimulus frequency($44.2{\pm}4.2%$ at 6/min to $271{\pm}86.7%$ at 180/min). Force-frequency relations were altered quantitatively during the perfusion with different external pH solutions. 5) Developed tension did not show marked variation within the range of $2{\sim}8\;mM$ potassium concentrations. Positive inotropism was observed at less than 2 mM $K^+$ and negative inotropism beyond 12 mM $K^+$ concentrations. From the above results we concluded that the effects of potassium ion concentration on electrical and mechanical properties of rabbit papillary muscle are related to the changes in surface negative charge due to acid base disturbances.

• The Korean Journal of Pharmacology
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• v.15 no.1_2 s.25
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• pp.29-37
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• 1979

The tension-length relationships and reactivity of vascular smooth muscle in longitudinal strips from portal vein ana in helical strips from thoracic aorta and pulmonary artery of normotensive control and cadmium-hypertensive rabbits were studied in vitro. 1. The mean arterial pressures of non-poisoned control rabbits was $87.0{\pm}4.7 mmHg$. However, Cd-poisoned group revealed the significant increase in pressure by $109.04{\pm}2.8 mmHg$ (p<0.005). 2. By tension-length studies, strips from portal vein of Cd-poisoned group stretched a greater percent increase in length in response to an applied resting force from 0.25 to 5 g than did those from non-poisoned group. On the contrary, strips from thoracic aorta of Cd-poisoned group showed less compliant than those from control, i.e. the former underwent a less percent increase in length than the latter. Passive tension-length relations of pulmonary artery was unaffected by Cd-hypertension. 3. The force of contraction(active tension) was significantly lowered in strips from aorta of Cd-hypertensive group throughout the range of $0.5{\sim}2g$ passive tension. However, there was no significant difference in the development of active tension of portal vein or pulmonary artery of both groups. 4. The $K^+$-contraction in the portal vein, aorta and pulmonary artery of Cd-poisoned group made no difference in the active force from those of control group. 5. The force of contraction in the strips from aorta of Cd-poisoned group was significanty decreased compared to that of control. The results suggested that the alterations in vascular reactivity to contracting substances and in distensibility to passive tension were induced in the Cd-hypertensive rabbits.

• The Journal of Internal Korean Medicine
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• v.11 no.1
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• pp.77-91
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• 1990

This study was carried out to investigate the effect of Jasoeumja extract on the contractile force of the isolated guinea pig trachea smooth muscle and elucidate its mechanism. The results were obtained as follows: 1. The isolated trachea smooth muscle was suspended in the Organ bath with oxygenated Kreb's Henseleit bicarbonate buffer solution at $37^{\circ}C$, and the developed tension by the drug was recorded with Isometric transducer (Nacro F-60). The resting tension was approximately 0.5g. 2. The trachea smooth muscle of the isolated guinea pig was significantly relaxed by the administration of Jasoeumja extract. 3. The contractile response of the trachea smooth muscle of the isolated guinea pig to histamine $10^{-4}M$ was significantly inhibited by Jasoeumja extract. 4. The contractile response of the trachea smooth muscle of the isolated guinea pig to acetylcholine $10^{-4}M$ was considerably inhibited by Jasoeumja extract. 5. The contractile response of the trachea smooth muscle of the isolated guinea pig to 5-hydroxytryptamine $10^{-4}M$ was considerably inhibited by Jasoeumja extract.

• The Journal of Internal Korean Medicine
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• v.11 no.2
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• pp.68-79
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• 1990

This study was carried out to investigate the effect of Heapyoyangjintang and Haepyoejintang extract on the contractile force of the isolated guinea pig trachea smooth muscle and elucidate its mechanism. The results were obtained as follows : 1. The isolated trachea smooth muscle was suspended in the organ bath with oxygenated kreb's Henseleit bicarbonate buffer solution at $37^{\circ}C$, and the developed tension by the drug was recorded with Isometric transducer(nacro F-60). The resting tension was approximately 0.5g. 2. The trachea smooth muscle of the isolated guinea pig was significantly relaxed by the administration of Haepyoyangjintang and Haepyoejintang extract. 3. The contractile response of the trachea smooth muscle of the isolated guinea pig to histamine$10^4M$ Was significantly inhibited by Heapyoyangjintang and Haepyoejintang extract. 4. The contractile response of the trachea smooth muscle of the isolated guinea pig to acetylcholine$10^4M$ was considerably inhibited by Haepyoyangjintang and Haepyoejintang extract. 5. The contractile response of the trachea smooth muscle of the isolated guinea pig to 5-hydorxytrtrypptamine $10^4M$ was considerably inhibited by Haepyoyangjintang and haepyoejintang extract.

• The Journal of Internal Korean Medicine
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• v.13 no.2
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• pp.84-94
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• 1992

This study was carried out to investigate the effect of samyootang and shinchulsan extract on the contractile force of the isolated guinea pig trachea smooth muscle and elucidate it's mechanism The isolated were obtained as follows ; 1. The isolated trachea smooth muscle was suspended in the organ bath with oxygenated kreb's Henseleit bicarbonate buffer solution at $37^{\circ}C$, and the developed tension by the drug was recored with Isometric transducer (nacro F-60) The resting tension was approximately 0.5g 2. The contractile response of the trachea smooth muscle of the isolated guinea pig to histamine $10^{-4}M$ was significantly inhibited by samyootang and shinchulsan extract. 3. The contractile response of the trachea smooth muscle of the isolated guinea pig to acetylcholine $10^{-4}M$ was considerably inhibited by samyootang and shinchulsan extract. 4. The contractile response of the trachea smooth muscle of the isolated guinea pig to histamine $10^{-4}M$ was significantly inhibited by samyootang and shinchulsan extract. 5. The contractile response of the trachea smooth muscle of the isolated guinea pig to acetylcholine $10^{-4}M$ was significantly inhibited by samyootang and shinchulsan extract.

• The Journal of Internal Korean Medicine
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• v.13 no.1
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• pp.99-109
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• 1992

In order to study the effects of Yunpaejaesueum known clinically for their effects of treatment for cough and asthma, the study was carried out to investigate the effect of Yunpaejaesueum extract on the contractile force of the isolated guinea pig trachea smooth muscle and elucidate its mechanism. The results were obtained as follows: 1. The isolated trachea smooth muscle of guinea pig was suspended in the organ bath with oxygenated Kreb's Henseleite bicarbonate buffer solution at $37^{\circ}C$, and the developed tension by the drug was recorded with isometric transducer(Nacro F-60). The resting tension was approximately 0.5g. 2. The isolated trachea smooth muscle of guinea pig was remakably relaxed by the administration of Yunpaejaesueum. 3. Yunpaejaesueum is significantly inhibited the contractile response of histimine 10-4 M in isolated guinea pig trachea smooth muscle. 4. Yunpaejaesueum is significantly inhibited the contractile response of acetylcholine 10-4 M in isolated guinea pig trachea smooth muscle. 5. Yunpaejaesueum is significantly inhibited the contractile response of 5-hydroxytryptamine 10-4 M in isolated guinea pig trachea smooth muscle. 6. Yunpaejaesueum is significantly inhibited the contractile response of prostaglandin F2a 10-7 M in isolated guinea pig trachea smooth muscle.

• The Journal of Internal Korean Medicine
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• v.13 no.1
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• pp.34-45
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• 1992

This study was carried out to investigate the effect of Shihogigiltang extract on the contractile force of the isolated guinea pig trachea smooth muscle and elucidate its mechanism. The results were obtained as follows: 1. The isolated trachea smooth muscle was suspended in the organ bath with oxygenated Kreb's Henseleit bicarbonate buffer solution at $37^{\circ}C$, and the developed tension by the drug was recorded with isometric transducer(Nacro F-60). The resting tension was approximately 0.5g. 2. The trachea smooth muscle of the isoiated guinea pig was significantly relaxed by the administration of Shihogigiltang extract. 3. ShihogigiItang significantly inhibited the contractile response of histamine 10-4 M is isolated guinea pig trachea smooth muscle. 4. The contractile response of the trachea smooth muscle of the isolated guinea pig by acetylcholine 10-4 M was significantly inhibited by Shihogigiltang extract. 5. The contractile response of the trachea smooth muscle of the isolated guinea pig by 5-hydorxytryptamine 10-4 M was significantly inhibited by Shihngigiltang extract. 6. The contractile response of the trachea smooth muscle of the isolated guinea pig by prostaglandin $F2\;{\alpha}$ 10-7 M was significantly inhibited by Shihngigiltang extract.