Effects of polyamines on contractility of guinea-pig gastric smooth muscle

Modulatory effect of intestinal polyamines and trace amines on the spontaneous phasic contractions of the isolated ileum and colon rings of mice

Background: Gastrointestinal motility modulatory factors include substances of the intestinal content, such as polyamines and trace amines (TAs), the focus of this study.

Methods: The amines of food, intestinal content and from faecal bacteria of Swiss mice were determined by HPLC and functionally characterised in isolated distal ileum and medial colon rings.

Results: Mouse food and intestinal content contain polyamines (spermidine>putrescine>spermine) and TAs (isoamylamine>cadaverine). Intestinal bacteria mainly produce putrescine and cadaverine. The amines inhibited the spontaneous motility of the ileum (0.1-3 mM) and colon rings (0.01-3 mM, with lower IC₅₀), with: spermine~isoamylamine~spermidine. Spermine inhibition was tetrodotoxin (TTX)-insensitive, while isoamylamine was TTX-sensitive, suggesting neural control. Mainly in the ileum, isoamylamine (3 mM) elicited acute effects modified by TTX, atropine and propranolol, and suppressed by spermine (3 mM), not being localized at the smooth muscle level. The amines assayed (3 mM), except putrescine and cadaverine in the ileum and isoamylamine in the colon, antagonised acetylcholine (ACh, 0.1 mM)-elicited phasic contractions. Isoamylamine and spermine in colon relaxed KCl (100 mM)-elicited tonic contractions, suggesting an effect on smooth muscle, but did not justify the suppression of motility caused by spermine and isoamylamine.

Conclusions: Polyamines and TAs of the intestinal content might act on chemosensors and modulate intestinal peristalsis.

Alterations in nerve-evoked bladder contractions in a coronavirus-induced mouse model of multiple sclerosis

BACKGROUND

Patients with neurodegenerative diseases such as multiple sclerosis, Parkinson's, and Alzheimer's often present with lower urinary tract symptoms (LUTS, urinary frequency, urgency, nocturia and retention) resulting from damage to the peripheral and central nervous systems. These studies were designed to examine the changes in the function of the bladder that may underlie neurogenic bladder dysfunction using a mouse model of demyelination in the CNS.

METHODS

Bladders from 12 week old male C57BL/6J mice with coronavirus-induced encephalomyelitis (CIE, a chronic, progressive demyelinating disease model of human MS), and age-matched controls, were cut into 5-7 strips and suspended in physiological muscle baths for tension measurement in response to agonists and electric field stimulation (EFS). Experiments were performed on intact and denuded (with mucosa removed) bladder strips.

RESULTS

The maximum effect of EFS was not significantly different between CIE and control bladders. Nerve-evoked EFS contractions (tetrodotoxin-sensitive) were blocked by a combination of atropine (cholinergic antagonist) and α,β-methylene ATP (an ATP analog that desensitizes purinergic receptors). In response to EFS, the α,β-methylene ATP-resistant (cholinergic) component of contraction was significantly reduced, while the atropine-resistant (purinergic) component was significantly increased in CIE bladders. Removal of the mucosa in CIE bladders restored the cholinergic component. Bethanechol (muscarinic receptor agonist) potency was significantly increased in CIE bladders.

CONCLUSIONS

Our data demonstrate a deficit in the nerve-evoked cholinergic component of contraction that is not due to the ability of the smooth muscle to respond to acetylcholine. We conclude that neurodegenerative bladder dysfunction in this model of multiple sclerosis may be due, in part, to pathologic changes in the mucosa that causes suppression of muscarinic receptor-mediated contractile response and augmentation of purinergic response of the underlying muscle. Further studies utilizing CIE mice should help elucidate the pathological changes in the mucosa resulting from demyelination in the CNS.

Analysis of hospital disaster in South Korea from 1990 to 2008

PURPOSE

The purpose of this study is to systematically review and analyze disasters involving South Korean hospitals from 1990 and to introduce a newly developed implement to manage patients' evacuation.

MATERIALS AND METHODS

We searched for studies reporting disaster preparedness and hospital injuries in South Korean hospitals from 1990 to 2008, by using the Korean Studies Information Service System (KISS, copyright Korean Studies Information Co, Ltd, Seoul, Korea) and, simultaneously, hospital injuries which were reported and regarded as a disaster. Then, each study and injury were analyzed.

RESULTS

Five studies (3 on prevention and structure, 1 on implement of new device, and 1 on basic supplement to current methods) and 8 injuries were found within this period. During the evacuations, the mean gait speed of walking patients was 0.82 m/s and the mean time of evacuation of individual patients was 38.39 seconds. Regarding structure evaluation, almost all hospitals had no balconies in patient rooms; hospital elevators were placed peripherally and were insufficient in number. As a new device, Savingsun (evacuation elevator) was introduced and had some merits as a fast and easy tool, regardless of patient status or the height of hospital.

CONCLUSION

In South Korea, preparation for hospital disasters was noted to be insufficient but has involved various departments such as architectural, clinical, and building operations. In addition, Savignsun has been shown to effectively evacuate and save patients in a hospital disaster.

Stejnihagin, a novel snake metalloproteinase from Trimeresurus stejnegeri venom, inhibited L-type Ca2+ channels

Snake venom metalloproteinases (SVMPs) mainly distribute in Crotalid and Viperid snake venom and are classified into the Reprolysin subfamily of the M12 family of metalloproteinases. Previous function investigations have suggested that SVMPs are the key toxins involved in a variety of snake venom-induced pathogenesis including systemic injury, local damage, hemorrhage, edema, hypotension, hypovolemia, inflammation and necrosis. However, up to now, there is no report on ion channels blocking activity about SVMPs. Here, from Trimeresurus stejnegeri venom we purified a component Stejnihagin containing a mixture of Stejnihagin-A and -B, with 86% sequences identity, both as members of SVMPs. In the study, whole-cell patch clamp and vessel tension measurement were employed to identify the effect of Stejnihagin on L-type Ca2+ channels and vessel contraction. The results show that Stejnihagin inhibited L-type Ca2+ channels in A7r5 cells with an IC50 about 37 nM and simultaneously blocked 60 mM K+-induced vessel contraction. Besides, the inhibitory effect of Stejnihagin on L-type Ca2+ channels was also independent of the enzymatic activity. This finding offers new insight into the snake venom metalloproteinase functions and provides a novel pathogenesis of T. stejnegeri venom. Furthermore, it may also provide a clue to study the structure-function relationship of animal toxins and voltage-gated Ca2+ channel.

Relaxant Effect of Spermidine on Acethylcholine and High K-induced Gastric Contractions of Guinea-Pig

In our previous study, we found that spermine and putrescine inhibited spontaneous and acetylcholine (ACh)-induced contractions of guinea-pig stomach via inhibition of L-type voltage-dependent calcium current (VDCC(L)). In this study, we also studied the effect of spermidine on mechanical contractions and calcium channel current (I(Ba)), and then compared its effects to those by spermine and putrescine. Spermidine inhibited spontaneous contraction of the gastric smooth muscle in a concentration-dependent manner (IC(50)=1.1+/-0.11 mM). Relationship between inhibition of contraction and calcium current by spermidine was studied using 50 mM high K(+)-induced contraction: Spermidine (5 mM) significantly reduced high K(+) (50 mM)-induced contraction to 37+/-4.7% of the control (p<0.05), and inhibitory effect of spermidine on I(Ba) was also observed at a wide range of test potential in current/voltage (I/V) relationship. Pre- and post-application of spermidine (5 mM) also significantly inhibited carbachol (CCh) and ACh-induced initial and phasic contractions. Finally, caffeine (10 mM)-induced contraction which is activated by Ca(2+)-induced Ca(2+) release (CICR),' was also inhibited by pretreatment of spermidine (5 mM). These findings suggest that spermidine inhibits spontaneous and CCh-induced contraction via inhibition of VDCC(L) and Ca(2+) releasing mechanism in guinea-pig stomach.