Vascular smooth muscle function

H27. Hollenberg, S. M., and Cunnion, R. E., Endothelial and vascular smooth muscle function in sepsis. J. Crit. Care 9,262-280 (1994). 

A high sodium intake and increased circulating natriuretic hormone inhibition of intracellular sodium transport, resulting in increased vascular reactivity and a rise in BP and / Increased intracellular concentration of calcium, leading to altered vascular smooth muscle function and increased peripheral vascular resistance. 

Blaustein MP, Golovina VA, Song H et al 2002 Organization of Ca2+ stores in vascular smooth muscle functional implications. In Role of the sarcoplasmic reticulum in smooth muscle. Wiley, Chichester (Novartis Found Symp 246) p 125-141 Karaki H, Ozaki H, Hori M et al 1997 Calcium movements, distribution and function in smooth muscle. Pharmacol Rev 49 157-230... 

Organization of Ca2+ stores in vascular smooth muscle functional implications... 

Triggle R, Tabrizchi R. 1993. Changes in vascular smooth muscle function in hypertension. Clin Med J 106 250-257. 

Increased intracellular concentration of calcium, leading to altered vascular smooth muscle function and increased peripheral vascular resistance. 

Karanian JW, and Salem N Jr. (1995). Hydroxylated 22-carbon fatty acids in platelet and vascular smooth muscle function interference with TXA2/PGH2 receptors. Agents Actions (Supplements) 45, 39-45. 

Altered calcium homeostasis also may play an important role in the pathogenesis of hypertension. A lack of dietary calcium hypothetically can disturb the balance between intracellular and extracellular calcium, resulting in an increased intracellular calcium concentration. This imbalance can alter vascular smooth muscle function by increasing peripheral vascular resistance. Some studies have shown that dietary calcium supplementation results in a modest BP reduction in hypertensive patients. 

Increased metabolism, increased heat production, weight loss, protrusion of the eyes (exophthalmia), and an increase in bone and muscle turnover are the major symptoms. In addition, increased levels of thyroid hormone have detrimental effects on cardiac muscle and cardiac conduction, as well as on vascular smooth muscle function. 

It is imperative to gain a better under.standing of how vascular smooth muscle, specifically the critical functional pathways, may be affected by OP chemtcal agents. Studies have been conducted within the context of the cardiovascular system that imply an acute alteration of vascular smooth muscle function. Whether this alteration has long-term ramifications in terms of irreversible detriment to functionally significant va.scular function remains to he determined. 

Prostacyclin also exerts potent effects on platelet and vascular smooth muscle function, both in vitro and following its administration in a number... 

Vanhoutte PM (1982) Role of the cmdothelinm in ctmtrol of vascular smooth muscle function. Veih K Acad Geneeskd Belg 44(5-6) 411-418... 

B. Influence of PO2 on Signaling Mechanisms That Regulate Vascular Smooth Muscle Function... 

In addition to intracellular heme-containing proteins, big-conductance calcium-dependent K+ (BKCa) channels and calcium-spark activated transient Kca channels in plasma membrane are also tar geted by CO [3]. As well known, nitric oxide (NO) also activates BKca channels in vascular smooth muscle cells. While both NO and CO open BKCa channels, CO mainly acts on alpha subunit of BKCa channels and NO mainly acts on beta subunit of BKca channels in vascular smooth muscle cells. Rather than a redundant machinery, CO and NO provide a coordinated regulation of BKca channel function by acting on different subunits of the same protein complex. Furthermore, pretreatment of vascular smooth muscle... 

Because of its motor, i.e., activating effect on vascular smooth muscle and its inhibitory effect on intestinal smooth muscle, the sympathetic nervous system has been cast into the role of the component of the nervous system that executes control of visceral function in times of physical emergency for the organism. The phrase fight or flight has been often used to describe the circumstances in which the adrenergic transmitters of the sympathetic system are dominant over the cholinergic parasympathetic system. This concept is perhaps oversimplified but it has the utility of a first approximation of how the two components of the ANS interact in the periphery. Sensory inputs which lead to increased blood pressure, for example, activate the sympathetic pathways. 

Nitric oxide is a regulator of vascular smooth muscle blockage of its formation from arginine causes an acute elevation of blood pressure, indicating that regulation of blood pressure is one of its many functions. 

Endothelin-1, one of the most potent physiologic vasoconstrictors, is an important contributor to HF pathophysiology.9 Endothelin-1 binds to two G-protein coupled receptors, endothelin-A (ET-A) and endothelin-B (ET-B). Endothelin-A receptors mediate vasoconstriction and are prevalent in vascular smooth muscle and cardiac cells. Endothelin-B receptors are expressed on the endothelium and in vascular smooth muscle, and receptor stimulation mediates vasodilation. Levels of ET-1 correlate with HF functional class and mortality. 

Schecter AD, Calderon I M, Berman AB, et al. Human vascular smooth muscle cells possess functional CCR5. J Biol Chem 2000 275(8) 5466-5471. 

Therefore, depending upon the degree of constriction of the vascular smooth muscle, these vessels may alter their diameter, and consequently their blood flow, across a very wide range. For this reason, the arterioles are the major resistance vessels in the circulatory system. In fact, the primary function of arterioles is to regulate the distribution of the cardiac output and to determine which tissues receive more blood and which receive less, depending upon the tissue s and the body s needs. 

In the periphery, 5-HT4 receptor mRNA is found in vascular smooth muscle. Newly developed drugs that activate 5-HT4 receptors are of interest for their potential in treating cardiac arrhythmia. The 5-HT4 receptor is also located on neurons of the alimentary tract, for example the myenteric plexus of the ileum, and on smooth muscle cells and secretory cells of the gastrointestinal tract, where they evoke secretions and the peristaltic reflex. 5-HT4 receptor agonists (e.g. cisapride, prucalopride, tegaserod) are used therapeutically in the treatment of constipation-predominant irritable bowel syndrome and in functional motility disorders of the upper gastrointestinal tract. 

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