Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Considerable experimental evidence has accumulated to indicate that brain ischemia or stroke-like events will lead to rapid losses of brain potassium, magnesium, ATP, creatine phosphate and glucose. These events are usually followed by an uptake of sodium and calcium ions. Increased uptake or excess Ca2+ uptake in neuronal cells is thought to be the prime cause of neuronal death in the brain. Mg2+ deficiency is known to produce a host of neurological disturbances in man; experimentally, Mg2+ deficiency leads to excess uptake of Ca2+ in the brain. Strokes and transient ischemic attacks also are known to be associated with neurological disturbances and ionic changes in the brain. Stroke patients have been reported to exhibit deficits in serum and CSF [Mg]. Acute Mg or K deficiency can produce cerebrovasospasm, at least experimentally. The lower the extracellular concentration of either Mg2+ or K+, the greater the magnitude of cerebral arterial contraction. These cerebrovascular contractions induced by lowering either the [Mg2+]0 or [K+]0 cannot be antagonized or attenuated by known pharmacologic antagonists. The cerebrovasospasms produced upon lowering [Mg2+]0 can be modulated by [K+]0 and vice versa; e.g. the lower the [K+]0, the greater the degree of vasospasm upon withdrawal of [Mg2+]0 and vice versa. Lowering [Mg2+]0 in situ and in vitro results in increased uptake of Ca2+ in the brain and the cerebral arteries. Cerebrovasospasms induced by substances that are known to be released in the brain on injury, such as prostanoids and serotonin, are relaxed dramatically by addition of [Mg2+]0. Infusions of MgSO4 into the brain via the internal carotid artery produces dose-dependent lowering of systolic and diastolic blood pressure as well as dose-dependent vasodilatation of arterioles (17-30 micron) and venules (18-40 micron) in the cerebral microcirculation, as observed by direct in situ high-resolution TV image-intensification microscopy. In clinical studies, infusion of MgSO4 has been reported to alleviate cerebrovasospasms. Epidemiological evidence is accumulating to suggest that consumption of fruit and vegetables (foodstuffs relatively high in K and Mg, and low in Na) is associated in certain geographic regions with a lower than normal incidence of strokes, particularly that of cerebral hemorrhage. On the basis of such data, and the findings reported herein, we believe one must consider that certain types of cerebrovascular accidents, transient ischemic attacks and 'classical' migraine attacks may be associated with a 'true' Mg deficiency and altered fluxes of K+ ions in the brain and CSF.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Interactions of Mg and K on cerebral vessels--aspects in view of stroke. Review of present status and new findings. 639 42

Electron probe microanalysis was employed to determine the elemental concentration (K,Na,Cl) in a myocyte on cryosections of the papillary muscle of the isolated rat (Wistar) heart. Protocols of global ischemia and ischemic conditions under glucose-free anoxic perfusion were applied. It was shown that global ischemia induces potassium deficiency (94 +/- 2 mM) in the myocyte and an increase in the level of sodium (72 +/- 4 mM) and chlorine (42 +/- 1 mM) in the cytoplasm compared with intact cell (122 +/- 2; 36 +/- 1; 24 +/- 1 mM). Glucose-free anoxic perfusion leads to a smooth fall of potassium concentration in the cell up to 54 +/- 2 mM with the retention of intracellular sodium (40 +/- 1 mM) and chlorine (26 +/- 1 mM) level. The present finding suggest that, in early ischemia, specific membrane mechanisms of ion transport are activated. Among these are KNa channel, Hi(+)-Nao+ exchange, KATP channel, lactate transport from the cell, associated either with potassium efflux to the extracellular space or chlorine influx into the myocyte. It is assumed that Na/K-ATPase is also activated under ischemic conditions.
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PMID:[Activation of specific membrane mechanisms in the myocardium cells on early stages of ischemia]. 1229 16

Acute myocardial infarction (AMI) is a highly dynamic event, which is associated with marked neuroendocrinological dysfunction in addition to cardiac damage. The immediate trigger for AMI is not precisely known. Studies conducted by Lown, Braunwald, Halberg, Otsuka and our group have demonstrated a marked increase in sympathetic activity, oxidative stress, and magnesium and potassium deficiency during AMI. Clinical studies have reported an increased incidence of AMI, sudden death and ischemia during first quarter of the day when there is a rapid withdrawal of vagal activity and increase in sympathetic tone. In one case-control study of 202 patients with AMI, there was a significant (P < 0.02) increase in cardiac events in the second quarter of the day compared to other quarters, respectively (16.8%, 41.0%, 13.8%, 28.2% per quarter). This characteristic remained prevalent in both men and women and among patients with and without known AMI (n = 52), diabetes (n = 53) or hypertension (n = 75). Triggers of AMI were noted among 162 (82.2%) of the patients. Neuropsychological mechanisms were observed as follows: emotional stress (45.5%), sleep deprivation (27.7%), cold climate (29.2%), hot climate (24.7%), large meals (47.5%) and physical exertion (31.2%). These triggering factors are known to enhance sympathetic activity and decrease vagal tone, resulting in an increased secretion of plasma cortisol, noradrenaline, aldosterone, angiotension-converting enzyme (ACE), interleukin (IL)-1, -2, -6, -18, and tumor necrosis factor-alpha (TNF-alpha), all of which are are proinflammatory agents. There is also a deficiency in the serum levels of vitamin A, E, and C and magnesium, potassium, melatonin, and IL-10 (an anti-inflammatory agent). In our study, we found a decrease in magnesium, potassium, vitamin A, E, C and beta carotene combined with an increase in thiobarbituric acid-reactive substances (TBARS), MDA and diene conjugates, TNF-alpha and IL-6, all of which are indicators of oxidative damage and proinflammatory activity, respectively.
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PMID:Mechanisms of acute myocardial infarction study (MAMIS). 1575 48

Electron probe microanalysis was applied to determine cytoplasmic elemental (K, Na, Cl) concentrations in cardiac cells of the rat (Wistar). Potassium, sodium and chlorine contents were measured in papillary muscle myocytes of the rat heart perfused by the Langendorff's procedure. Ischemic depletion was created by perfusion with deeply deoxygenated Tirode's solution in the absence of glucose. It was found that the initial phase of acute ischemia is characterized by the potassium deficiency and the accumulation of sodium and chlorine in cardiac myocytes. It should be noted that changes in the total charge of the main intracellular cations (K+, Na+) do not compensate for the increased chlorine concentration. This result can be accounted for by the appearance of ionic (K+ and Cl-) transport coupled with the removal of lactate anions produced in cardiomyocytes during anaerobic glycolysis.
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PMID:[Electron probe microanalysis of potassium, sodium, and chlorine levels in the cardiomyocyte cytoplasm during acute ischemia]. 2103 55

Electron probe microanalysis was applied to study the kinetics of changes in potassium and sodium concentration in muscle cells of isolated heart from Wistar rat during experimental ischemia. Hypoxic perfusion without glucose was shown to evoke the potassium deficiency and sodium accumulation in cardiac myocells. Short-term action (10 min) of strophanthin (0.1 mM/l) recovered Na/K balance in ischemic myocells. Hypothermic perfusion exhibited the opportunity to conserve the cytoplasmic elemental contents in the state corresponding to the beginning of low temperature (4 degrees C) operation.
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PMID:[Nonspecific effect of Na+/K(+)-ATPase inhibition with strophanthin or under hypothermia in rat heart]. 2573 Sep 78