• The Korean Journal of Physiology and Pharmacology
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• v.3 no.4
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• pp.439-445
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• 1999

This study is to investigate the mechanism of inhibitory effect of imipramine on the calcium utilization in single cells isolated from canine detrusor. 2 mm thick smooth muscle chops were incubated in 0.12% collagenase solution at $36^{circ}C,$ and aerated with 95% $O_2/5%\;CO_2,$ and then cell suspension was examined. Acetylcholine (ACh) evoked a concentration-dependent contraction of the isolated detrusor cells in normal physiologic salt solution (PSS), and the ACh-induced contraction was significantly inhibited by imipramine. In $Ca^{2+}-free$ PSS, ACh-induced contraction was less than those in normal PSS and it was not affected by the pretreatment with imipramine. $Ca^{2+}-induced$ contraction in $Ca^{2+}-free$ PSS was supressed by imipramine, but addition of A 23187, a calcium ionophore, overcomed the inhibitory effect of imipramine. High potassium-depolarization (40 mM KCl) evoked cell contraction, which was inhibited by imipramine. Caffeine, a releasing agent of the stored $Ca^{2+}$ from sarcoplasmic reticulum, evoked a contraction of the cells that was not blocked by the pretreatment with imipramine. These results suggest that imipramine inhibits the influx of calcium in the detrusor cells through both the receptor-operated- and voltage-gated-calcium channels, but does not affect the release of calcium from intracellular storage site.

• The Korean Journal of Pharmacology
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• v.31 no.2
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• pp.195-206
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• 1995

The study was undertaken to examine the possibility of the involvement of $K^+$ channels in the mechanism of relaxant-action of imipramine on the isolated canine detrusor muscle strips. Canine urinary bladder were isolated, and smooth muscle strips of 15 mm long and 2 mm wide from the mid-portion of anterior wall were made in the Tyrode solution of $0{\sim}4^{\circ}C$. The strips were prepared for isometric myography in Biancani's isolated muscle chamber containing 1 ml of Tyrode solution, which was maintained with pH 7.4 by aeration with $95%\;O_2/5%CO_2\;at\;37^{\circ}C$. RP 52891, a non-specific $K^+$ channel opener, concentration-dependently suppressed the spontaneous phasic contractions of the detrusor strips. Imipramine, a tricyclic antidepressant, also reduced the spontaneous contractions in a concentration-dependent manner. RP 52891 was more potent than imipramine(p<0.05), and Imipramine was more efficient than RP 52891(p<0.05).Procaine, a voltage-dependent $K^+$ channel blocker, glibenclamide, an ATP-dependent $K^+$ channel blocker, and apamin, a calcium-dependent $K^+$ channel blocker antagonized the relaxant effect of RP 52891, but not of imipramine. Imipramine reduced the electric field stimulation (EFS) -induced contractions concentration-dependently. None of the $K^+$ channel blockers employed for this study, procaine, glibenclamide or apamin antagonized the inhibitory action of imipramine on the EFS-induced contraction. These results suggest that in canine detrusor, the $K^+$ channels of the characteristics of voltage-dependent, ATP-dependent and/or calcium-dependent are exist, and the inhibitory action of imipramine on the contractility of the detrusor is independent from the $K^+$ channels.

• Journal of Yeungnam Medical Science
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• v.11 no.2
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• pp.293-302
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• 1994

The objective of this study was to establish a good methodology to isolate single smooth muscle cells that are alive and respond properly to pharmacological agents. Canine urinary bladders were employed as the source of single cells, and acetylcholine, atropine and imipramine were used as indicators of pharmacological responsiveness. Imipramine, an antidepressant drug exhibited the anticholinergic and calcium antagonizing properties on rat detrusor muscle. To establish a control value for a further experiment to elucidate the mechanism of action of imipramine on detrusor muscle, we measured the concentration-response of single cells to acetylcholine in the presesnce of imipramine by length of the cells and compared the result with the response in the presence of atropine. Tiny chops of smooth muscle taken from anesthetized canine urinary bladder were incubated in collagenase solution at $36^{\circ}C$ for 17-20 minutes. The collagenase solution included collagenase 1.2 mg/ml, soybean tryspin inhibitor 0.08 mg/ml, bovine serum albumin 2% in 10 ml Krebs-Henseleit buffer solution aerated with a consistent breeze of 95/5% $O_2/CO_2$, to maintain the pH at 7.4. After washing with plain K-H solution on 450 mesh, cells were dissociated from the digested tissue for 12-15 minutes. Cell suspension was transfered in 5 ml test tubes and acetylcholine was added for the final concentration to be $10^{-14}M{\sim}10^{-9}M$. To find the optimal time to fix the cells to determine the contractile responses, 1% acrolein was added 5, 10, 20, 30, 60 and 120 seconds after the administration of ACh. The length of cells fixed by acrolein were measured by microscaler via CCTV camera on phaes-contrast microscope. The average length of 50 cells from a slide glass was taken as the value of a sample at the very concentration point. Single cells were isolated from canine detrusor. The length of untreated cells varied from 82 ${\mu}m$ to 94 ${\mu}m$. The maximal response to actylcholine $10^{-9}M$ was accomplished within 5 seconds of exposure, and the shortening was $19{\pm}3$%. Atropine reduced the contraction of the cells concentration-dependently. Imipramine which exerts a cholinergic blocking action on some smooth muscles also reduced the contraction concentration-dependently and by a similar pattern as atropine. These findings document that imipramine may exerts a cholinergic blocking activity in the single smooth muscle cells isolated from canine urinary bladder.