The functional responses of different overnight-stored in vitro tissues are not clearly described in any animal model. The influence of overnight storage in an animal model may vary between tissue types. We employed Sprague-Dawley rat as our animal model and investigated the functional changes of rat aorta, trachea, bronchus and bladder that were used (i) immediately after surgical removal (denoted as fresh) and (ii) after storage in aerated (95% O2, 5% CO2) Krebs-Ringer bicarbonate solution at 4 °C for 24 h (denoted as stored). The aorta ring was pre-contracted with phenylephrine, and the functional response of the tissue was investigated using isoprenaline, forskolin and carbachol. Carbachol was also used to increase the tone in trachea, bronchus rings and bladder strips. A clear reduced function of endothelium, with a minor if any effect in the smooth muscle function in rat aorta was observed after overnight storage. The contractile response of overnight-stored rat airway (trachea and bronchus) and bladder smooth muscles remained unchanged. Among all tested tissues, only bronchus showed a reduced response rate (only 40% responded) after storage. In vitro rat tissues that are stored in Krebs solution at 4 °C for 24 h can still be used to investigate smooth muscle responses, however, not endothelium-mediated responses for aorta. The influence of overnight storage on different tissues from an animal model (Sprague-Dawley rat in our study) also provides an insight in maximising the use of sacrificed animals.
This paper is a review on the types of antagonists and the signaling mechanism pathways that have been used to determine the mechanisms of action employed for vasodilation by test compounds. Thus, we exhaustively reviewed and analyzed reports related to this topic published in PubMed between the years of 2010 till 2015. The aim of this paperis to suggest the most appropriate type of antagonists that correspond to receptors that would be involved during the mechanistic studies, as well as the latest signaling pathways trends that are being studied in order to determine the route(s) that atest compound employs for inducing vasodilation. The methods to perform the mechanism studies were included. Fundamentally, the affinity, specificity and selectivity of the antagonists to their receptors or enzymes were clearly elaborated as well as the solubility and reversibility. All the signaling pathways on the mechanisms of action involved in the vascular tone regulation have been well described in previous review articles. However, the most appropriate antagonists that should be utilized have never been suggested and elaborated before, hence the reason for this review.
Renal angiomyolipoma, once considered a rare benign renal tumour, is relatively common these days. They account for 0.3-3.0% of all renal masses. Histologically, it is composed of adipose tissue, smooth muscles and blood vessels. Here, we wish to highlight five cases of renal angiomyolipomas which were presented to the University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia, over a two-year period between June 2005 and June 2007. This study wish to illustrate its varied clinical presentation and the management undertaken for each underlying condition. These cases were presented in the form of spontaneous perirenal haemorrhage, a large asymptomatic renal mass, a small asymptomatic renal mass, a symptomatic renal angiomyolipoma and a case of renal angiomyolipoma mimicking a renal tumour. Each of these cases varied in its clinical presentation; thus, management has become very challenging to clinicians ranging from conservative management to active intervention, be it operatively or non-operatively.
Laryngeal leiomyosarcoma is a rare smooth muscle malignancy of the head and neck region. Diagnosis is based on immunohistochemistry. Here we present a case of laryngeal leiomyosarcoma that was diagnosed and treated in our center, focusing on the clinical features, histological diagnosis and management of this rare disease.
Restenosis represents a major impediment to the success of coronary angioplasty. Abnormal proliferation of vascular smooth muscle cells (VSMCs) has been shown to be an important process in the pathogenesis of restenosis. A number of agents, particularly rapamycin and paclitaxel, have been shown to impact on this process. This study was carried out to determine the mechanisms of cytotoxicity of goniothalamin (GN) on VSMCs. Results from MTT cytotoxicity assay showed that the IC(50) for GN was 4.4 microg/ml (22 microM), which was lower compared to the clinically used rapamycin (IC(50) of 25 microg/ml [27.346 microM]). This was achieved primarily via apoptosis where up to 25.83 +/- 0.44% of apoptotic cells were detected after 72 h treatment with GN. In addition, GN demonstrated similar effects as rapamycin in inhibiting VSMCs proliferation using bromodeoxyuridine (BrdU) cell proliferation assay after 72 h treatment at IC(50) concentration (p > 0.05). In order to understand the mechanisms of GN, DNA damage detection using comet assay was determined at 2h post-treatment with GN. Our results showed that there was a concentration-dependent increase in DNA damage in VSMCs prior to cytotoxicity. Moreover, GN effects were comparable to rapamycin. In conclusion, our data show that GN initially induces DNA damage which subsequently leads to cytotoxicity primarily via apoptosis in VSMCs.
In an attempt to pharmacologically characterize the Chinese antihypertensive drug, tetrandrine, we observed in rat-tail arteries, an unusual contraction in tissues that were stimulated with high [KCl] and not those stimulated with phenylephrine. The characteristics of this contraction were studied.
The quest for improving and maintaining sexual function has been going on since time immemorial. The advent of an effective oral drug, sildenafil, has brought about unprecedented open discussion on male erectile dysfunction, and gas accelerated the pace of development of new therapies for erectile dysfunction. New knowledge in the physiology of sexual function has enabled researchers to target drug treatment at the whole network of the central nervous system and the numerous cascadic enzymatic reactions leading to relaxation of the corporal smooth muscle. One of the brightest potential applications of future molecular technology in the study of erectile dysfuction is in the utilization of gene therapy.
The effect of the total glysosidic extract of the plant Sarcolobus globosus was investigated on the contractions of the smooth muscle of the guinea-pig ileal longitudinal muscle and taenia coli. In the ileal longitudinal muscle, addition of the extract inhibited the electrical field-stimulated twitches. Similarly to verapamil, it also reduced the contractions of the muscle to acetylcholine, histamine and KCl. However, only the tonic contraction to KCl was reversed by increasing the extracellular calcium concentration. In the taenia coli, lower concentrations of both the extract and verapamil induced a parallel displacement of the dose-response curves to calcium (0.30-30 mM). Addition of the extract also dose-dependently inhibited the KCl-induced contraction of the taenia coli. Increasing the calcium concentration increased the IC50 values of the extract. The result suggests that the inhibitory effect of the Sarcolobus globosus extract on the smooth muscle, like verapamil, is mainly due to inhibition of calcium influx.
Breast hamartoma is an uncommon poorly recognised benign breast neoplasm. Hamartoma displaying marked smooth muscle components known as myoid hamartoma of the breast is a much rarer entity. We present a case of myoid hamartoma of breast with chondroid differentiation in a 46-year-old woman. The painless breast lump was circumscribed and mammography showed a well-encapsulated large, dense mass with no calcification. Core needle biopsy was reported as fibroadenoma. The lesion was excised. Microscopically, it composed of many groups of mammary glandular components with dense fibrous stroma, adipose tissue and marked groups of smooth muscle fibres. Foci of chondroid differentiation were noted in the lesion. The smooth muscle cells showed strong and diffuse immunoreactivity for vimentin, myogloblin, alpha-smooth muscle actin, desmin and CD34 and failed to express pan-cytokeratin or S100 protein. The ducts lined by epithelial cells were reactive to pan-cytokeratin while the myoepithelial cells were reactive to S100 protein. The various immuno-histochemical staining as well as the cyto-histological changes encountered in myoid hamartomas are discussed with clinical, radiological and pathological correlation to differentiate it from other benign and malignant breast lesions.
Dicentrine is a known alpha 1-adrenoceptor antagonist, but its alpha 1-adrenoceptor subtype selectivity has not yet been determined. We therefore, investigated the putative alpha 1-adrenoceptor subtype selectivity of this agent.
Myogenic tone is the response of the vascular smooth muscle to an increase in intraluminal pressure with vasoconstriction and with vasodilation when the pressure is decreased. Such myogenic tone contributes a level of physiological basal tone in response to neurohumoral stimuli. In spite of myogenic tone discovery by Sir William Bayliss 100 years ago, questions still remain regarding the underlying signaling mechanism of the myogenic response. Studies have shown that increased intraluminal pressure or wall tension leads to membrane depolarization, voltage-operated calcium channel (VOCC), stretch-activated cation (SAC) channels, extracelullar matrix (ECM) and actin cytoskeleton. Recently, evidence has shown a potential role for reactive oxygen species (ROS) as a key signalling mediator in the genesis of myogenic tone. The identification of the primary mechanosensors in the initiation of pressure-dependent myogenic tone is essential as these components could be potential therapeutical targets in the future.
Asthma is considered as heterogeneous multidimensional disorder due to variable phenotypic presentation. Phenotype is defined as a cluster of either clinical or pathologic features, which tends to be associated with the understanding the mechanisms of the disease. Asthma is typically characterized by airway inflammation, variable airway obstruction, bronchial hyper-reactivity, smooth muscle hypertrophy and apparent reversible airflow obstruction by bronchodilators. ‘Asthma syndrome’ is a term to describe complex pathophysiology of the condition which is not exclusive to allergen triggered episodes. Diagnosing childhood asthma is difficult, due to the similarity of symptoms and overlapping with other wheezing conditions. The precise mechanism for asthma exacerbation, for each individual phenotype is not fully understood. However, it is influenced by genetic interaction with variety of external environmental stimuli. The current understanding on asthma phenotypes were interpreted based on age of onset, associated triggers, clinical aspects, physiologic parameters and type of inflammation (Table 1). Due to the illdefined of the current phenotypic definition and disagreement among the respirologists, it is becoming a challenge to label specific phenotype with certainty. Accurate definition of each phenotype should therefore be helpful to provide better understanding of different mechanistic pathways and focusing on targeted therapy for individual phenotype. (Copied from article).
Adipose tissue provides an abundant source of multipotent cells, which represent a source of cell-based regeneration strategies for urinary bladder smooth muscle repair. Our objective was to confirm that adipose-derived stem cells (ADSCs) can be differentiated into smooth muscle cells.
A study of 101 sera from 69 Malay, 14 Chinese and 18 Indian healthy adult Malaysians was undertaken to determine the frequency of antinuclear antibodies (ANA), antimitochondrial antibodies (AMA), antismooth muscle antibodies (SMA) and antiparietal cell antibodies (APCA). There were 67 females and 34 males with a mean age of 31.7 years (+/-8.6). ANA was assayed by immunofluorescence (IF) using both mouse liver and HEp-2 cell substrates. AMA, SMA and APCA were also tested by IF using composite sections from mouse liver, kidney and stomach substrates. Analysis showed 6.9% were positive for ANA at a titre of 1:40 with HEp-2 while only 1.9% were detected using mouse liver. 9.9% had detectable AMA from titres 1:10 to 1:90. None of them had detectable SMA and only 1 (0.09%) had APCA at a titre of 1:80. This study suggests that a diagnosis of an autoimmune disorder has to be cautiously made taking into consideration that autoantibodies are present in low titres in the healthy population.
1. Male Sprague-Dawley rats were made either hyper- or hypothyroid with thyroxine or 4-methyl-2-thiouracil, respectively. Bronchial smooth muscle (BSM) contractility and lung cyclic adenosine 3',5'-monophosphate (cAMP) content were measured in both conditions. 2. Bronchial smooth muscle contractility was significantly weaker in hyperthyroid rats, while the BSM contractility of hypothyroid rats was the same as controls. 3. The cAMP content of hyperthyroid rat lungs was similar to controls but was decreased in hypothyroid rats. 4. These studies demonstrated that both the hyper- and hypothyroid states affect respiration, although the mechanisms involved with different for each condition.
We have investigated the effect of indomethacin on histamine- and acetylcholine (ACh)-induced responses in the intact and denuded epithelium of guinea pig isolated tracheal smooth muscle. Epithelium removal resulted in increased responsiveness to ACh and histamine. Indomethacin (2.8 microM) enhanced the sensitivity of both intact and denuded preparations to histamine and ACh. These findings suggest that the tracheal epithelium of guinea pig plays a protective role against bronchoconstrictors, such as ACh and histamine. Furthermore, indomethacin-mediated hyperresponsiveness caused by these agonists in epithelium denuded preparations might be a reflection of removal of prostaglandin (PG) biosynthesis. A similar process of interaction in indomethacin-treated asthmatic patients (with damaged airway epithelium) might take place. The significance of these findings is discussed.
Atherosclerosis commences with the trapping of low density lipoproteins (LDLs) in blood vessels by modified proteoglycans (PGs) with hyperelongated glycosaminoglycan (GAG) chains. GAG chain synthesis and growth factor mediated hyperelongation regulates the composition and size of PGs in a manner that would cause low density lipoprotein (LDLs) retention in vessel wall. Galactosaminoglycans are a class of GAGs, commonly observed on PGs. Multiple enzymes are involved in galactosaminoglycan biosynthesis. Galactosaminoglycan synthesis is regulated by various signalling pathways which are amenable to pharmacological manipulation to treat atherosclerosis. Receptor mediated signalling pathways including protein tyrosine kinase receptors (PTKRs), serine/threonine kinase receptors (S/TKRs) and G-protein coupled receptors (GPCRs) pathways regulate galactosaminoglycan synthesizing enzyme expression. Increased expression of these enzymes modify galactosaminoglycan chain structure by making them hyperelongated. This review focuses on the signalling pathways regulating the expression of genes involved in galactosaminoglycan synthesis and modification. Furthermore, there are multiple other processes for inhibiting the interactions between LDL and galactosaminoglycans such as peptide mimetics of ApoB100 and anti-galactosaminoglycan antibodies and the therapeutic potential of these strategies is also addressed.
PREMISES AND OBJECTIVES: Antioxidant plays an important role in preventing the progression of diabetes mellitus (DM) complications. The aim of the present study was to investigate the effect of alpha lipoic acid (ALA) supplementation on plasma lipid, oxidative stress and vascular changes in diabetic rats.
1. The effects of corticosteroid pretreatment on acetylcholine (ACH)-induced contraction of bronchial smooth muscle (BSM) were studied. 2. ACH dose-response curves for dexamethasone (DM)- and corticosterone (B)-treated but not deoxycorticosterone (DOC)-treated BSM were significantly shifted to the right; this provides evidence that glucocorticoid treatment reduced the sensitivity of BSM to ACH. 3. Morphine enhanced BSM contraction in response to ACH by 20%. DM suppressed this enhancement. 4. These findings correlated well with the reduction of muscarinic receptor numbers in BSM by glucocorticoids in our previous study. In addition, glucocorticoids reduced the sensitivity of BSM to opioids.
1. Glucocorticosteroid may relieve bronchospasm by mediating changes in the muscarinic receptor concentration and/or its affinity. 2. Cholinergic muscarinic receptors were determined by using Scatchard's plots from radioligand binding assays of 0.13-3.2 nM [3H]quinuclidinyl benzylate binding to the membrane fraction of bronchial smooth muscle (BSM). 3. The concentration of muscarinic receptor in BSM of normal rat was 57 +/- 3 fmol mg protein and the dissociation constant was 0.07 +/- 0.02 nM. Dexamethasone and corticosterone reduced muscarinic receptor concentration to 50-60% of basal with no changes in receptor affinity. No changes were found in rat treated with deoxycorticosterone. 4. These findings suggest that glucocorticoids but not mineralocorticoid relieve bronchospasm at least partly by reducing the cholinergic hypersensitivity.