• Korean Journal of Veterinary Research
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• v.39 no.4
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• pp.702-709
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• 1999

The present study was performed to elucidate the effects of extracellular $Ca^{2+}$ on contractile responses in isolated porcine coronary artery ring using by perivascular nerve stimulation (PNS). Especially, the study was focused on the source of $Ca^{2+}$ on $P_{2X}$-purinoceptor mediated muscle contraction which one of $P_2$-purinoceptor subtypes. The following results can be drawn from these studies : 1. The phasic contractions induced by PNS were inhibited with muscarinic receptor antagonist, atropine ($10^{-6}M$). 2. The phasic contractions induced by PNS were significantly inhibited by sequential treatment with atropine and adrenergic neural blocker, guanethidine ($10^{-6}M$). 3. The phasic contractions induced by PNS were inhibited with $P_{2X}$-purinoceptor desensitization by repetitive application of $\alpha$,$\beta$-Me ATP ($10^{-4}M$). 4. The phasic contractions induced by PNS were so weakened in calcium-free medium. 5. The phasic contractions induced by PNS were inhibited with calcium channel blocker, verapamil ($10^{-6}{\sim}5{\times}10^{-6}M$). 6. The phasic contractions induced by PNS on pretreated with verapamil ($10^{-6}{\sim}5{\times}10^{-6}M$) were not changed by $\alpha$,$\beta$-Me ATP ($10^{-4}M$). These results demonstrate that the neurogenic phasic contractions induced by PNS are due to adrenergic-, cholinergic- and $P_{2X}$-purinergic receptors and the origin of $Ca^{2+}$ on $P_{2X}$-purinoceptor mediated muscle contraction is extracellular $Ca^{2+}$ through plasmalemmal $Ca^{2+}$ channels.

• YAKHAK HOEJI
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• v.41 no.6
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• pp.797-801
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• 1997

Recently we reported that water extracts of Coptidis Rhizomas showed calcium antagonistic action and alpha-adrenoceptor inhibitory action in the vascular smooth muscle. Since ca lcium antagonistic properties are important in the treatment of various diseases including asthma. In the present study, the bronchodilatory effects of crude extract of three kinds of Coptidis Rhizoma (Coptidis chinensis, Coptis japonica and root hair of Coptis japonica) was investigated using rat isolated trachea. The result showed that all extracts relaxed carbachol-contracted tracheal smooth muscle. Concentration-dependently, in which the root hair of Coptis japonica was the least potent. The inhibitory potency expressed in terms of $IC_{50}$ against carbachol contraction was 1.8${\mu}$g/ml and 2.7${\mu}$g/ml for Coptidis chinensis and Coptis japonica, respectively. These extracts also inhibited KCI-contracted tracheal smooth muscle. But the relative potency ($IC_{50}$) was 3.5 and 4.1 folds weaker than carbachol-induced contraction for Coptidics chinenesis and Coptis japonica, respectively. Pretreatment of crude extracts also inhibited carbachol- or KCI-induced contraction, non-competitively. These findings indicate that the extracts have muscarinic blocking as well as $Ca^{2+}$ channel blocking action. When provoked intracellular stored $Ca^{2+}$ release by carbachol in $Ca^{2+}$-free conditions, initial phasic contraction due to $Ca^{2+}$ release was significantly inhibited by the extracts. As taken together, we conclude that water extracts of Coptidis Rhizoma may be beneficial in bronchospasm or other broncheal tube narrowing conditions such as asthma.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.5
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• pp.265-272
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• 2004

The present study was attempted to investigate the effect of cilnidipine (FRC-8635), which is a newly synthesised novel dihydropyridine (DHP) type of organic $Ca^{2+}$ channel blockers, on secretion of catecholamines (CA) evoked by acetylcholine (ACh), high $K^+$, DMPP and McN-A-343 from the isolated perfused rat adrenal gland. Cilnidipine $(1{\sim}10{\mu}M)$ perfused into an adrenal vein for 60 min produced relatively dose- and time-dependent inhibition in CA secretory responses evoked by ACh $(5.32{\times}10^{-3}M),\;DMPP\;(10^{-4}M\;for\;2\;min)$ and McN-A-343 $(10^{-4}M\;for\;2\;min)$. However, lower dose of cilnidipine did not affect CA secretion by high $K^+\;(5.6{\times}10^{-2}\;M)$, higher dose of it reduced greatly CA secretion of high $K^{+}$. Cilnidipine itself did fail to affect basal catecholamine output. In the presence of cilnidipine $(10{\mu}M)$, the CA secretory responses evoked by Bay-K-8644 $(10{\mu}M)$, an activator of L-type $Ca^{2+}$ channels and cyclopiazonic acid $(10{\mu}M)$, an inhibitor of cytoplasmic $Ca^{2+}$-ATPase were also inhibited. Moreover, ${\omega}-conotoxin\;GVIA\;(1{\mu}M)$, a selective blocker of the N-type $Ca^{2+}$ channels, given into the adrenal gland for 60 min, also inhibited time-dependently CA secretory responses evoked by Ach, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid. Taken together, these results demostrate that cilnidipine inhibits CA secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors from the isolated perfused rat adrenal gland without affecting the basal release. However, at lower dose, cilnidipine did not affect CA release by membrane depolarization while at larger dose inhibited that. It seems likely that this inhibitory effect of cilnidipine is exerted by blocking both L- and N-type voltage-dependent $Ca^{2+}$ channels (VDCCs) on the rat adrenomedullary chromaffin cells, which is relevant to inhibition of both the $Ca^{2+}$ influx into the adrenal chromaffin cells and intracellular $Ca^{2+}$ release from the cytoplasmic store. It is thought that N-type VDCCs may play an important role in regulation of CA release from the rat adrenal medulla.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.4
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• pp.155-164
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• 2008

Resveratrol has been known to possess various potent cardiovascular effects in animal, but there is little information on its functional effect on the secretion of catecholamines (CA) from the perfused model of the adrenal medulla. Therefore, the aim of the present study was to determine the effect of resveratrol on the CA secretion from the isolated perfused model of the normotensive rat adrenal gland, and to elucidate its mechanism of action. Resveratrol (10${\sim}100{\mu}$M) during perfusion into an adrenal vein for 90 min inhibited the CA secretory responses evoked by ACh (5.32 mM), high $K^+$ (a direct membrane-depolarizer, 56 mM), DMPP (a selective neuronal nicotinic $N_n$ receptor agonist, 100${\mu}$M) and McN-A-343 (a selective muscarinic $M_1$ receptor agonist, 100${\mu}$M) in both a time- and dose- dependent fashion. Also, in the presence of resveratrol (30${\mu}$M), the secretory responses of CA evoked by veratridine 8644 (an activator of voltage-dependent$Na^+$ channels, 100${\mu}$M), Bay-K-8644 (a L-type dihydropyridine $Ca^{2+}$ channel activator, 10${\mu}$M), and cyc1opiazonic acid (a cytoplasmic $Ca^{2+}$-ATPase inhibitor, 10${\mu}$M) were significantly reduced. In the simultaneous presence of resveratrol (30${\mu}$M) and L-NAME (an inhibitor of NO synthase, 30${\mu}$M), the CA secretory evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyc1opiazonic acid were recovered to a considerable extent of the corresponding control secretion compared with the inhibitory effect of resveratrol alone. Interestingly, the amount of nitric oxide (NO) released from the adrenal medulla was greatly increased in comparison to its basal release. Taken together, these experimental results demonstrate that resveratrol can inhibit the CA secretory responses evoked by stimulation of cholinergic nicotinic receptors, as well as by direct membrane-depolarization in the isolated perfused model of the rat adrenal gland. It seems that this inhibitory effect of resveratrol is exerted by inhibiting an influx of both ions through $Na^+$ and $Ca^{2+}$ channels into the adrenomedullary cells as well as by blocking the release of $Ca^{2+}$ from the cytoplasmic calcium store, which are mediated at least partly by the increased NO production due to the activation of NO synthase.

• The Korean Journal of Pharmacology
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• v.31 no.1 s.57
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• pp.27-37
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• 1995

In anesthetized rats, we examined the possibility that endothelium-derived relaxing factor (EDRF) or nitric oxide (NO) released in response to cholinergic mechanism may contribute to the reflex autoregulation of cerebral blood flow. Suffusion with mock cerebrospinal fluid (CSF), containing acetylcholine (ACh, $10^{-9}{\sim}10^{-6}M$) evoked concentration-dependent vasodilatation of the resting pial artery (mean, $19.3{\pm}1.7{\mu}m$, n=36), which was significantly inhibited not only by $N{\omega}$-nitro-L-arginine (L-NNA, $10^{-5}M$) but also by methylene blue ($10^{-6}M$) and oxyhemoglobin ($10^{-6}M$). The muscarinic receptors in the endothelium of pial artery implicated in the release of EDRF were considered to be $M_1\;and\;M_3$ subtypes. When suffused with mock CSF containing L-arginine it caused a transient vasodilatation, which was strongly inhibited by LY 83583 ($10^{-5}M$), but not by L-NNA ($10^{-5}M$). Additionally, both ACh- and L-arginine-induced vasodilation were significantly inhibited by glibenclamide, a specific ATP-sensitive $K^+$ channel blocker. On the other hand, changes in pial arterial diameter were plotted as a function of changes in systemic arterial blood pressure. The slopes of regression lines for vasodilation and vasoconstriction were not affected by pretreatment with $10^{-5}M$ L-NNA, but significantly reduced by $3{\times}10^{-6}M$ glibenclamide. Thus it is suggested that the reflex vasodilation of rat pial arteries in response to a transient hypotension is not mediated by EDRF (NO).

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.6
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• pp.629-639
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• 2016

The present study was designed to investigate the characteristics of gintonin, one of components isolated from Korean Ginseng on secretion of catecholamines (CA) from the isolated perfused model of rat adrenal gland and to clarify its mechanism of action. Gintonin (1 to $30{\mu}g/ml$), perfused into an adrenal vein, markedly increased the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. The gintonin-evoked CA secretion was greatly inhibited in the presence of chlorisondamine ($1{\mu}M$, an autonomic ganglionic bloker), pirenzepine ($2{\mu}M$, a muscarinic $M_1$ receptor antagonist), Ki14625 ($10{\mu}M$, an $LPA_{1/3}$ receptor antagonist), amiloride (1 mM, an inhibitor of $Na^+/Ca^{2+}$ exchanger), a nicardipine ($1{\mu}M$, a voltage-dependent $Ca^{2+}$ channel blocker), TMB-8 ($1{\mu}M$, an intracellular $Ca^{2+}$ antagonist), and perfusion of $Ca^{2+}$-free Krebs solution with 5mM EGTA (a $Ca^{2+}$chelater), while was not affected by sodium nitroprusside ($100{\mu}M$, a nitrosovasodialtor). Interestingly, LPA ($0.3{\sim}3{\mu}M$, an LPA receptor agonist) also dose-dependently enhanced the CA secretion from the adrenal medulla, but this facilitatory effect of LPA was greatly inhibited in the presence of Ki 14625 ($10{\mu}M$). Moreover, acetylcholine (AC)-evoked CA secretion was greatly potentiated during the perfusion of gintonin ($3{\mu}g/ml$). Taken together, these results demonstrate the first evidence that gintonin increases the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. This facilitatory effect of gintonin seems to be associated with activation of LPA- and cholinergic-receptors, which are relevant to the cytoplasmic $Ca^{2+}$ increase by stimulation of the $Ca^{2+}$ influx as well as by the inhibition of $Ca^{2+}$ uptake into the cytoplasmic $Ca^{2+}$ stores, without the increased nitric oxide (NO). Based on these results, it is thought that gintonin, one of ginseng components, can elevate the CA secretion from adrenal medulla by regulating the $Ca^{2+}$ mobilization for exocytosis, suggesting facilitation of cardiovascular system. Also, these findings show that gintonin might be at least one of ginseng-induced hypertensive components.

• The Korean Journal of Pharmacology
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• v.31 no.1 s.57
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• pp.63-74
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• 1995

It has been known that, during hypoxia, the adrenal medulla is activated to release catecholamines (CA) while hypoxia also inhibits high $K^+$ -induced CA secretion in the cultured bovine adrenal chromaffin cells. The present study was attempted to examine the effect of hypoxia on CA secretion evoked by chlinergic stimulation and membrane-depolarization from the isolated perfused rat adrenal glands and also to clarify its mechanism of action. For this purpose, using the isolated rat adrenal glands, the effects of hypoxia on CA release evoked by nicotinic ($N_1$) and muscarinic ($M_1$) receptor agonists, membrane-depolarizing agent, $Ca^{++}$-channel activator, intracellular $Ca^{++}$-releaser and ACh were determined. Experiments were carried out, perfusing Krebs solution pre-equilibrated with a gas mixture of 95% N_2$ and 5% $CO_2$. Hypoxia was maintained for $3{\sim}4$ hours through the experiments. Hypoxia gradually caused a time-dependent seduction in CA secretion evoked by DMPP ($100{\mu}M$), McN-A-343 ($100{\mu}M$), ACh (5.32 mM), Bay-K-8644 ($10{\mu}M$) and high $K^+$ (56 mM) respectively. How-ever, it did not affect CA secretion evoked by cyclopiazonic acid ($10{\mu}M$). Hypoxia itself also did fail to produce any influence on spontaneous secretory response of CA. These experimental results suggest that hypoxia depresses CA release evoked by both cholinergic stimulation and membrane-depolarization from the isolated rat adrenal medulla, and that this inhibitory activity may be due to the result of the direct inhibition of $Ca^{++}$ influx into the chromaffin cells without any effect on the calcium mobilization from the intracellular store.

• The Korean Journal of Pharmacology
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• v.28 no.1
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• pp.81-89
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• 1992

Enuresis is a common voiding disorder among children. There are several therapeutic regimens for the disorder available today; behavioral therapies, psychotherapy, bladder training, sleep interruption, hypnosis and drug therapy. Recently, the efficacy of drug therapy has been acknowledged, particularly of antidepressants. Among the tricyclic antidepressants, imipramine is most frequently employed for the treatment of enuresis. Present study was undertaken to investigate the mechanism of imipramine on the contractility of urinary bladder in relation to the calcium modulation using isolated strips of rat detrusor urinae. 1. The electric fileld stimulation-induced contraction was abolished by imipramine, but partially inhibited by atropine. 2. Imipramine reduced the basal tone and diminished the phasic activity of detrusor muscle concentration-dependently, which was similar to that of diltiazem, a calcium channel blocker. 3. Imipramine suppressed the maximal responses and shifted the concentration-response curves of bethanechol and ATP to right. 4. Imipramine inhibited the calcium-induced recovery of tension in calcium-free physiologic salt solution (PSS) with a mode of action similar to that of diltizaem. 5. A23187, a calcium ionophore recovered the basal tone which had been reduced by imipramine in normal PSS. 6. In calcium-free PSS, A23187 could recover the abolished basal tone with the pretreatment of imipramine, but it exerted a partial recovery with the pretreatment of TMB-8, an inhibitor of intracellular calcium release. Based on these results, it is suggested that the inhibitory action of imipramine on the detrusor muscle exerted in part by blockade of the muscarinic and purinergic receptors, and interference with the influx of extracellular calcium, but not with the release of intracellular stored calcium, is involved in its mechanism of action.