Smooth muscle contractility

Somatostatin acts on various organs, tissues and cells as neurotransmitter, paracrine/autocrine and endocrine regulator on cell secretion, smooth muscle contractility, nutrient absorption, cell growth and neurotransmission [1]. Some of its mainly inhibitory effects are listed in Table 1. Somatostatin mediates its function via a family of heptahelical G-protein-coupled receptors termed... 

Asthma is a complex respiratory disorder that involves mast cell degranulation, mucous secretions, and smooth muscle hypertrophy and hyperresponsiveness. Smooth muscle hyperresponsiveness has suggested some defect in the regulation of smooth muscle contractility. Therefore, a number of studies concerning asthma have centered on whether alterations in the regulation of smooth muscle contraction (Figure 4) are responsible for hyperactivity in asthmatic airway smooth muscle. 

List the factors that may alter smooth muscle contractile activity... 

All of these factors (ANS stimulation, blood-borne and locally produced substances) alter smooth muscle contractile activity by altering the intracellular concentration of calcium. An increase in cytosolic calcium leads to an increase in crossbridge cycling and therefore an increase in tension... 

Mast cell-dependent alterations in smooth muscle contractility and intestinal permeability may also be important in expulsion of H. polygyms and T. spiralis. Increases in smooth muscle contractility (with associated... 

Herrera MD, Zarzuelo A, Jimenez J, Marhuenda E, Duarte J. 1996. Effects of flavonoids on rat aortic smooth muscle contractility structure-activity relationships. Gen Pharmacol 27 273-277. 

Obviously, the effects of tamoxifen and derivatives and of raloxifene on L-type calcium channels from aortic and other blood vessels would reduce vascular smooth muscle contractility. This action, in synergy with the aforementioned effect on BK channels, would reduce blood peripheral resistance and blood pressure, which may partially account for the reduction in cardiovascular risk (Da Costa et al. 2004 Trump et al. 1992) (Fig. 4.1). 

Taggart MJ, Wray S 1998 Contribution of sarcoplasmic reticular calcium to smooth muscle contractile activation gestational dependence in isolated rat uterus. J Physiol 511 133—144... 

Holton My understanding is that the vena cava is a tonic smooth muscle, and therefore it is right at one end of a spectrum of smooth muscle contractile types. This means that, it generates tension slowly, it maintains tension when it is activated and it doesn t show action potentials. Its organization may be very different from a phasic smooth muscle that normally operates by action potentials and cannot maintain tension. 

Nicholls and Skidmore (65) demonstrated that dust collected from mills with a higher prevalence of byssinosis caused greater smooth muscle contractile activity than dust from mills with a lower prevalence. Recently, Russell e al. (66) used an isolated tissue bath to measure canine trachealis muscle contraction caused by cotton bract extracts (CBE). Morey et al. (67) showed that cotton bract represents 20-43% of the cotton dust total thus, the findings of Paton and Davenport using cotton dust agree in principle with Russell e al., who used cotton bract. Davenport and Paton (62) found a percentage of the activity of CDE represented by a 5HT-like component, but they also found at least one more active substance in the CDE than Russell et al. (66). 

Hernandez R, Vuelvas A, Garcia A, Fragoso M, Pereda R, Ibarra C, Rojas A (2008) Calcium-Dependent Effect of Tricolorin A on Intestinal and Arterial Smooth Muscle Contractility. 7th Joint Meeting of AFERP, ASP, GA, PSE and SIE. Planta Med 74 973... 

Available evidence suggests that a single unifying mechanism does not exist but rather that various vasodilators may act at different places in the series of processes that couple excitation of vascular smooth muscle cells with contraction. For example, the vasodilators known as calcium channel antagonists block or limit the entry of calcium through voltage-dependent channels in the membrane of vascular smooth muscle cells. In this way, the calcium channel blockers limit the amount of free intracellular calcium available to interact with smooth muscle contractile proteins (see Chapter 14). 

Muscarinic receptors play a key role in many functions in the periphery and the central nervous system. In the periphery, muscarinic receptors are involved in cardiac function, glandular secretion, and smooth muscle contractility. Central muscarinic receptors modulate pain... 

Arachidonic acid released from membrane phospholipids or other sources is metabolized by the LO pathway to the smooth muscle contractile and vasoactive leukotrienes (LT), LTC4, and LTD4, as well as to the potent chemoattractant LTB4. These molecules are intimately involved in inflammation, asthma, and allergy, as well as in other multiple physiological and pathological processes. For example, cirsiliol (3, 4, 5-trihydroxy-6,7-dimethoxyflavone) proved to be a potent inhibitor of 5-LO (IC50, 0.1 pM) derived from basophilic leukemia cells and peritoneal polymorphonuclear leukocytes. 

Relative activities are from Cushman and Ondetti (72). The activity of each peptide to increase the smooth muscle contractile action of bradykinin was determined relative to SQ20,881 (100%). 

Hollenberg, M.D. 1994. Tyrosine kinase pathways and the regulation of smooth muscle contractility. Trends Pharmacol Sci 15 108-114. 

Based on this, one would predict that treatment of intact smooth muscle preparations with an inhibitor of CaMKII should potentiate myosin light chain phosphorylation and the rapid phase of force development. In contrast, we have found that in carotid arterial smooth muscle, KN-93 inhibition of CaMKII activation in response to physiological contractile stimuli correlates with a marked inhibition of tonic force responses (Rokolya and Singer 2000), suggesting an alternative dominant action of CaMKII on the smooth muscle contractile apparatus. 

Smith PG, Moreno R, Ikebe M. Strain increases airway smooth muscle contractile and cytoskeletal proteins in vitro. Am J Physiol Lung Cell Mol Physiol. 1997 272(16) L20-L27. 

Saponara S, Kawase M, Shah A, Motohashi N, Molnar J, Ugocsai K, Sgaragli G, Fusi F (2004) 3,5-Dibenzoyl-4-(3-phenoxyphenyl)-l,4-dihydro-2,6-dimethylpyridine (DP7) as a new multidrug resistance reverting agent devoid of effects on vascular smooth muscle contractility. Br J Pharmacol 141 415-422... 

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