• The Korean Journal of Physiology and Pharmacology
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• v.9 no.4
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• pp.223-230
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• 2005

The purpose of the present study was to examine the effect of naltrexone, an opioid antagonist, on secretion of catecholamines (CA) evoked by cholinergic nicotinic stimulation and membrane-depolarization from the isolated perfused rat adrenal gland and to establish the mechanism of its action. Naltrexone $(3{\times}10^{-6}M)$ perfused into an adrenal vein for 60 min produced time-dependent inhibition in CA secretory responses evoked by ACh $(5.32{\times}10^{-3}M)$ , high $K^+$ $(5.6{\times}10^{-2}M)$ , DMPP ($10^{-4}$ M) and McN-A-343 $(10^{-4}M)$ . Naltrexone itself did also fail to affect basal CA output. In adrenal glands loaded with naltrexone $(3{\times}10^{-6}M)$ , the CA secretory responses evoked by Bay-K-8644, an activator of L-type $Ca^{2+}$ channels and cyclopiazonic acid, an inhibitor of cytoplasmic $Ca^{2+}-ATPase$, were also inhibited. However, in the presence of met-enkephalin $(5{\times}10^{-6}M)$ , a well-known opioid agonist, the CA secretory responses evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid were also significantly inhibited. Collectively, these experimental results demonstrate that naltrexone inhibits greatly CA secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors as well as that by membrane depolarization. It seems that this inhibitory effect of naltrexone does not involve opioid receptors, but might be mediated by blocking both the calcium influx into the rat adrenal medullary chromaffin cells and the uptake of $Ca^{2+}$ into the cytoplasmic calcium store, which are at least partly relevant to the direct interaction with the nicotinic receptor itself.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.4
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• pp.231-238
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• 2003

The present study was undertaken to investigate the effect of bradykinin on secretion of catecholamines (CA) evoked by stimulation of cholinergic receptors and membrane depolarization from the isolated perfused model of the rat adrenal glands, and to elucidate its mechanism of action. Bradykinin $(3{\times}10^{-8}M)$ alone produced a weak secretory response of the CA. however, the perfusion with bradykinin $(3{\times}10^{-8}M)$ into an adrenal vein of the rat adrenal gland for 90 min enhanced markedly the secretory responses of CA evoked by ACh $(5.32{\times}10^{-3}M)$, excess $K^+$ ($5.6{\times}10^{-2}M$, a membrane depolarizer), DMPP ($10^{-4}$ M, a selective neuronal nicotinic agonist) and McN-A-343 ($10^{-4}$ M, a selective M1-muscarinic agonist). Moreover, bradykinin ($3{\times}10^{-8}$ M) in to an adrenal vein for 90 min also augmented the CA release evoked by BAY-K-8644, an activator of the dihydropyridine L-type $Ca^{2+}$ channels. However, in the presence of $(N-Methyl-D-Phe^7)$-bradykinin trifluoroacetate salt $(3{\times}10^{-8}M)$, an antagonist of $BK_2$-bradykinin receptor, bradykinin no longer enhanced the CA secretion evoked by Ach and high potassium whereas the pretreatment with Lys-$(des-Arg^9,\;Leu^9)$-bradykinin trifluoroacetate salt $(3{\times}10^{-8}M)$, an antagonist of $BK_1$-bradykinin receptor did fail to affect them. Furthermore, the perfusion with bradykinin $(3{\times}10^{-6}M)$ into an adrenal vein of the rabbit adrenal gland for 90 min enhanced markedly the secretory responses of CA evoked by excess $K^+$ $(5.6{\times}10^{-2}M)$. Collectively, these experimental results suggest that bradykinin enhances the CA secretion from the rat adrenal medulla evoked by cholinergic stimulation (both nicotininc and muscarinic receptors) and membrane depolarization through the activation of $B_2$-bradykinin receptors, not through $B_1$-bradykinin receptors. This facilitatory effect of bradykinin seems to be associated to the increased $Ca^{2+}$ influx through the activation of the dihydropyridine L-type $Ca^{2+}$ channels.

• Archives of Pharmacal Research
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• v.28 no.6
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• pp.699-708
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• 2005

The present study was designed to investigate the effect of naloxone, a well known opioid antagonist, on the secretion of catecholamines (CA) evoked by cholinergic stimulation and membrane-depolarization in the isolated perfused rat adrenal glands, and to establish its mechanism of action. Naloxone ($10^{-6}\~10^{-5}$ M), perfused into an adrenal vein for 60 min, produced dose- and time-dependent inhibition of CA secretory responses evoked by ACh ($5.32\times10^{-3}$ M), high K+ ($5.6\times10^{-2}$ M), DMPP ($10^{-4}$ M) and McN-A-343 ($10^{-4}$ M). Naloxone itself also failed to affect the basal CA output. In adrenal glands loaded with naloxone ($3\times10^{-6}$ M), the CA secretory responses evoked by Bay-K-8644, an activator of L-type $Ca^{2+}$ channels, and cyclopiazonic acid, an inhibitor of cytoplasmic $Ca^{2+}$-ATPase, were also inhibited. In the presence of met-enkephalin ($5\times10^{-6}$ M), a well known opioid agonist, the CA secretory responses evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid were also significantly inhibited. Taken together, these results suggest that naloxone greatly inhibits the CA secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors as well as that by membrane depolarization. It seems that these inhibitory effects of naloxone does not involve opioid receptors, but might be mediated by blocking both the calcium influx into the rat adrenal medullary chromaffin cells and the uptake of $Ca^{2+}$ into the cytoplasmic calcium store, which are at least partly relevant to the direct interaction with the nicotinic receptor itself.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.87-100
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• 1994

It has been known for some time that dopamine-containing cells are existed in sympathetic ganglia, i.e., small, intensely fluorescent cells. However, its role and mechanism of action as a peripheral neurotransmitter are poorly understood so far. In the present study, an attempt was made to examine the effect of apomorphine, which is known to be a selective agonist of dopaminergic $D_2$. receptor on secretion of catecholamines (CA) from the isolated perfused rat adrenal gland. The perfusion of a low concentration of 10uM apomorphine into an adrenal vein for 20 min produced significant reduction in CA secretion induced by 5.32 mM ACh, 56 mM KCl, 100 uM DMPP and 100 uM McN-A-343. Increasing apomorphine concentration to 30 uM led to more markedly decreased CA secretion as compared to the case of 10 uM apomorphine and also did inhibit clearly CA release by $10^{-5}M$ Bay-K-8644. Furthermore, in adrenal glands preloaded with a higher dose of 100 uM apomorphine, CA releases evoked by ACh, excess $K^+$, DMPP and McN-A-343 were almost abolished by the drug. The perfusion of $3.3{\pm}10^{-5}M$ metoclopramide, which is well-known as a selective dopaminergic $D_2$ antagonist, produced significantly inhibitory effect of CA release by ACh, DMPP and McN-A-343 but did not affect that by excess $K^+$. However, preloading of 30uM apomorphine in the presence of metoclopramide did not modify the CA secretory effect of excess $K+$ and DMPP. These experimental results demonstrate that apomorphine causes dose-dependent inhibition of CA secretion by cholinergic receptor stimulation and also by membrane depolarization from the isolated perfused rat adrenal gland, suggesting that these effects appear to be exerted by inhibiting influx of extracellular calcium into the rat adrenal medullary chromaffin cells through activation of inhibitory dopaminergic receptors.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.1
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• pp.21-30
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• 2007

The present study was designed to establish comparatively the inhibitory effects of cilnidipine(CNP), nifedipine(NIF), and $\omega$-conotoxin GVIA(CTX) on the release of CA evoked by cholinergic stimulation and membrane depolarization from the isolated perfused model of the rat adrenal medulla. CNP(3 ${\mu}M$), NIF(3 ${\mu}M$), and CTX(3 ${\mu}M$) perfused into an adrenal vein for 60 min produced greatly inhibition in CA secretory responses evoked by ACh($5.32{\times}10^{-3}M$), DMPP($10^{-4}M$ for 2 min), McN-A-343($10^{-4}M$ for 2 min), high $K^+(5.6{\times}10^{-2}M)$, Bay-K-8644($10^{-5}M$), and cyclopiazonic acid($10^{-5}M$), respectively. For the CA release evoked by ACh and Bay-K-8644, the following rank order of potency was obtained: CNP>NIF>CTX. The rank order for the CA release evoked by McN-A-343 and cyclopiazonic acid was CNP>NIF>CTX. Also, the rank orders for high $K^+$ and for DMPP were NIF>CTX>CNP and NIF>CNP>CTX, respectively. Taken together, these results demonstrate that all voltage-dependent $Ca^{2+}$ channels(VDCCs) blockers of cilnidipine, nifedipine, and $\omega$-conotoxin GVIA inhibit greatly the CA release evoked by stimulation of cholinergic(both nicotinic and muscarinic) receptors and the membrane depolarization without affecting the basal release from the isolated perfused rat adrenal gland. It seems likely that the inhibitory effects of cilnidipine, nifedipine, and $\omega$-conotoxin GVIA are mediated by the blockade of both L- and N-type, L-type only, and N-type only VDCCs located on the rat adrenomedullary chromaffin cells, respectively, which are relevant to $Ca^{2+}$ mobilization. It is also suggested that N-type VDCCs play an important role in the rat adrenomedullary CA secretion, in addition to L-type VDCCs.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.126.1-126.1
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• 2003

Adrenal medullary chromaffin cells secrete catecholamines in response to nicotinic agonists (Douglas ＆ Rubin. 1961; Wakade, 1981; Amy ＆ Kirshner, 1982). Several types of voltage-dependent Ca2+ channels are present on adrenal chromaffin cells, but the role of each type in the catecholamine secretion process remains controversial. (omitted)

• Natural Product Sciences
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• v.13 no.1
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• pp.68-77
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• 2007

The aim of the present study was to examine the effects of green tea extract (CUMS6335) on the release of CA evoked by cholinergic stimulation and direct membrane-depolarization in the perfused model of the adrenal gland isolated from the spontaneously hypertensive rats (SHRs), and to establish the mechanism of action. Furthermore, it was also to test whether there is species difference between animals, and between CUMS6335 and EGCG, one of biologically the most powerful catechin compounds found in green tea. CUMS6335 $(100\;{\mu}g/ml)$, when perfused into an adrenal vein for 60 min, time-dependently inhibited the CA secretory responses evoked by ACh (5.32mM), high $K^+$(56 mM), DMPP $(100\;{\mu}M)$, and McN-A-343 $(100\;{\mu}M)$ from the isolated perfused adrenal glands of SHRs. However, CUMS6335 itself did fail to affect basal catecholamine output. Also, in adrenal glands loaded with CUMS6335 $(100\;{\mu}g/ml)$, the CA secretory responses evoked by Bay-K-8644 $(10\;{\mu}M)$ and cyclopiazonic acid $(10\;{\mu}M)$ were also inhibited in a relatively time-dependent fashion. However, in the Presence of EGCG $(8.0\;{\mu}g/ml)$ for 60 min, the CA secretory response evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid were not affected except for last period. Collectively, these results indicate that CUMS6335 inhibits the CA secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors as well as by direct membrane-depolarization from the perfused adrenal gland of the SHR. It seems that this inhibitory effect of CUMS6335 is exerted by blocking both the calcium influx into the rat adrenal medullary chromaffin cells and the uptake of $Ca^{2+}$ into the cytoplasmic calcium store, which are at least partly relevant to the direct interaction with the nicotinic receptor itself. It seems likely that there is much difference in mode of the CA-releasing action between CUMS6335 and EGCG.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.1
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• pp.45-53
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• 2005

The present study was designed to examine the effect of d-amphetamine on CA release from the isolated perfused model of the rat adrenal gland, and to establish its mechanism of action. Damphetamine $(10{\sim}100{\mu}M$), when perfused into an adrenal vein of the rat adrenal gland for 60 min, enhanced the CA secretory responses evoked by ACh ($5.32{\times}10^{-3}$ M), excess $K^+$ ($5.6{\times}10^{-2}$ M, a membrane depolarizer), DMPP ($10^{-4}$ M, a selective neuronal nicotinic $N_n-receptor$ agonist) and McN-A-343 ($10^{-4}$ M, a selective $M_1-muscarinic$ agonist) only for the first period (4 min), although it alone has weak effect on CA secretion. Moreover, d-amphetamine ($30{\mu}M$) in to an adrenal vein for 60 min also augmented the CA release evoked by BAY-K-8644, an activator of the dihydropyridine L-type $Ca^{2+}$ channels, and cyclopiazonic acid, an inhibitor of cytoplasmic $Ca^{2+}$ ATPase only for the first period (4 min). However, in the presence of high concentration ($500{\mu}M$), d-amphetamine rather inhibited the CA secretory responses evoked by the above all of secretagogues. Collectively, these experimental results suggest that d-amphetamine at low concentrations enhances the CA secretion from the rat adrenal medulla evoked by cholinergic stimulation (both nicotininc and muscarinic receptors) as well as by membrane depolarization, but at high concentration it rather inhibits them. It seems that d-amphetamine has dual effects as both agonist and antagonist at nicotinic receptors of the isolated perfused rat adrenal medulla, which might be dependent on the concentration. It is also thought that these actions of d-amphetamine are probably relevant to the $Ca^{2+}$ mobilization through the dihydropyridine L-type $Ca^{2+}$ cha$N_n$els located on the rat adrenomedullary chromaffin cell membrane and the release of $Ca^{2+}$ from the cytoplasmic store.

• Biomolecules & Therapeutics
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• v.16 no.2
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• pp.147-160
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• 2008

The present study was designed to examine effects of polyphenolic compounds isolated from red wine (PCRW) on the release of catecholamines (CA) from the isolated perfused model of the rat adrenal medulla, and to clarify its mechanism of action. PCRW (20${\sim}$180 ${\mu}$g/mL), given into an adrenal vein for 90 min, caused inhibition of 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 dose- and time-dependent fashion. PCRW itself did not affect basal CA secretion (data not shown). Following the perfusion of PCRW (60 ${\mu}$g/mL), the secretory responses of CA evoked by Bay-K-8644 (a L-type dihydropyridine $Ca^{2+}$ channel activator, 10 ${\mu}$M), cyclopiazonic acid (a cytoplasmic $Ca^{2+}$-ATPase inhibitor, 10 ${\mu}$M) and veratridine (an activator of voltage-dependent $Na^+$ channels, 10 ${\mu}$M) were also markedly blocked, respectively. Interestingly, in the simultaneous presence of PCRW (60 ${\mu}$g/mL) and L-NAME (a selective inhibitor of NO synthase, 30 ${\mu}$M), the inhibitory responses of PCRW on the CA secretion evoked by ACh, high $K^+$, DMPP, McN-A-343, Bay-K-8644 and cyclpiazonic acid were recovered to considerable level of the corresponding control release compared with those effects of PCRW-treatment alone. Practically, the amount of NO released from adrenal medulla after loading of PCRW (180 ${\mu}$g/mL) was significantly increased in comparison to the corresponding basal released level. Collectively, these results obtained here demonstrate that PCRW inhibits the CA secretory responses evoked by stimulation of cholinergic (both muscarinic and nicotinic) receptors as well as by direct membrane-depolarization from the isolated perfused adrenal gland of the normotensive rats. It seems that this inhibitory effect of PCRW is mediated by blocking the influx of both ions through $Na^+$ and $Ca^+{2$} channels into the rat adrenomedullary chromaffin cells as well as by inhibiting the release of $Ca^{2+}$ from the cytoplasmic calcium store, which are due at least partly to the increased NO production through the activation of nitric oxide synthase. Based on these data, it is also thought that PCRW may be beneficial to prevent or alleviate the cardiovascular diseases, such as hypertension and angina pectoris.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.1
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• pp.99-109
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• 2013

The aim of this study was to determine whether fimasartan, a newly developed $AT_1$ receptor blocker, can affect the CA release in the isolated perfused model of the adrenal medulla of spontaneously hypertensive rats (SHRs). Fimasartan (5~50 ${\mu}M$) perfused into an adrenal vein for 90 min produced dose- and time-dependently inhibited the CA secretory responses evoked by ACh (5.32 mM), high $K^+$ (56 mM, a direct membrane depolarizer), DMPP (100 ${\mu}M$) and McN-A-343 (100 ${\mu}M$). Fimasartan failed to affect basal CA output. Furthermore, in adrenal glands loaded with fimasartan (15 ${\mu}M$), the CA secretory responses evoked by Bay-K-8644 (10 ${\mu}M$, an activator of L-type $Ca^{2+}$ channels), cyclopiazonic acid (10 ${\mu}M$, an inhibitor of cytoplasmic $Ca^{2+}$-ATPase), and veratridine (100 ${\mu}M$, an activator of $Na^+$ channels) as well as by angiotensin II (Ang II, 100 nM), were markedly inhibited. In simultaneous presence of fimasartan (15 ${\mu}M$) and L-NAME (30 ${\mu}M$, an inhibitor of NO synthase), the CA secretory responses evoked by ACh, high $K^+$, DMPP, Ang II, Bay-K-8644, and veratridine was not affected in comparison of data obtained from treatment with fimasartan (15 ${\mu}M$) alone. Also there was no difference in NO release between before and after treatment with fimasartan (15 ${\mu}M$). Collectively, these experimental results suggest that fimasartan inhibits the CA secretion evoked by Ang II, and cholinergic stimulation (both nicotininc and muscarinic receptors) as well as by membrane depolarization from the rat adrenal medulla. It seems that this inhibitory effect of fimasartan may be mediated by blocking the influx of both $Na^+$ and $Ca^{2+}$ through their ion channels into the rat adrenomedullary chromaffin cells as well as by inhibiting the $Ca^{2+}$ release from the cytoplasmic calcium store, which is relevant to $AT_1$ receptor blockade without NO release.