Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Physiological and biochemical processes which take place in the nervous system at stroke and neurotrauma are reviewed, and the experience of using low doses of steroid derivatives with piridamole in the treatment of central nervous system (CNS) disorders is summarized. ATPases (including Na,K-ATPase) are reported to play an important role in CNS functioning, the correlation between Na,K-ATPase activity and the extent of CNS injury is revealed. The use of NMR-spectroscopy method for investigation of brain and spinal cord condition in vivo is suggested.
 ...
PMID:[The role of carrier ATPases and neuromediators in neurological disorders]. 197 89

In order to evaluate the possibility of left ventricular assistance by latissimus dorsi (LD) myograft, we have studied contractile property and fatigue rates of skeletal muscle ventricle (SMV) constructed using canine LD muscles. Twenty three dogs were divided into 3 groups depending on the conditioning protocol of LD muscles; Group I (Control n = 12), Group II (Vascular delay n = 4) and Group III (Vascular delay and electrical preconditioning n = 7). SMVs in GIII dogs generated sufficient pressure and forward flow in a hydraulic test system with muscle stimulation at a burst-frequency of 50 Hz (SMV pressure 131 +/- 42 mmHg, Stroke volume 7.0 +/- 3.0 ml/beat). Although SMVs in GI and GII dogs could sustain flow for only 4.0 +/- 1.1 minutes and 32.4 +/- 14.0 minutes, respectively, SMVs in GIII were able to pump continuously for 107.5 +/- 15.0 minutes (p less than 0.01, vs GI and GII). Thermography surface temperature mapping revealed marked improvement of blood distribution of LD muscles in GII and GIII dogs. Flow rates of thoracodorsal artery during SMV stimulation were GI: 10.0 +/- 3.1 ml/minute/LD 100 g, GII: 15.0 +/- 3.7 ml/minutes/100 g and GIII: 20.7 +/- 2.5 ml/minutes/100 g (p less than 0.01 vs GI). The ratio of oxygen consumption to lactate output was GI: 0.33 +/- 0.10, GII: 0.36 +/- 0.09 and GIII: 1.56 +/- 0.97 (p less than 0.01 vs GI, p less than 0.05 vs GII). Histochemical examination of LD muscles using alkaline ATPase stain revealed muscle fiber type transformation of GIII muscles. These results suggest electrically preconditioned LD muscles have sufficient contractile property for partial left ventricular assistance, and highly fatigue-resistant properties resulted from muscle fiber transformation, improved muscle perfusion and metabolic changes.
 ...
PMID:[Potential for left ventricular assistance by latissimus dorsi myograft--sequential effects of electrical preconditioning on skeletal muscle fiber type, blood flow and metabolic status]. 205 Oct 85

In order to study the mechanochemical coupling in actomyosin energy transduction, the sliding distance of an actin filament induced by a myosin head during one ATP hydrolysis cycle was obtained using an in vitro movement assay, which permitted quantitative and simultaneous measurements of (1) the movements of single fluorescently-labeled actin filaments on myosin bound to coverslip surfaces and (2) the ATPase rates. The sliding distance was determined as (the working-stroke time in one ATPase cycle, Tws) x (the filament velocity, v). The working-stroke time (Tws) was obtained from the ATPase turnover rate of myosin during the sliding (kT), the ATP hydrolysis time on myosin heads (delta T) and the ON-rate at which myosin heads enter into the working-stroke when they encounter actin (kON); Tws approximately 1/kT-delta T-1/kON. kON was estimated by analyzing the movements of very short (40 nm) filaments. The resulting sliding distance during one ATP hydrolysis cycle near zero load was greater than 100 nm, which is about 10 times longer than that expected for a single attachment-detachment cycle between an actin monomer and a myosin head. This leads to the conclusion that the coupling between the chemical and mechanical reactions is not rigid in a one to one fashion.
 ...
PMID:Loose coupling between chemical and mechanical reactions in actomyosin energy transduction. 208 30

Effects of carbacyclin, a synthetic analogue of prostacyclin on Na, K-ATPase, Ca, Mg- and Ca-ATPase activity of plasmatic membrane (PM) and sarcoplasmic reticulum (SR) of the heart normotensive (WKY) and stroke-prone spontaneously hypertensive (SHR-SP) rats were examined. In SR carbacyclin was found to increase Ca, Mg- and Ca-ATPase activity in SHR-SP and decrease the activity of this enzymes in WKY. Carbacyclin caused identical effect on ATPase activity in PM in WKY and SHR-SP, but the greatest effects were in WKY.
 ...
PMID:[The effect of carbacyclin on the ATPase activity in the heart of normotensive and spontaneously hypertensive rats with a hereditary susceptibility to stroke]. 214 5

In order to study the mechanochemical coupling in actomyosin energy transduction, the sliding distance of an actin filament induced by one ATP hydrolysis cycle was obtained by using an in vitro movement assay that permitted quantitative and simultaneous measurements of (1) the movements of single fluorescently labeled actin filaments on myosin bound to coverslip surfaces and (2) the ATPase rates. The sliding distance was determined as (the working stroke time in one ATPase cycle, tws) x (the filament velocity, v). tws was obtained from the ATPase turnover rate of myosin during the sliding (kt), the ATP hydrolysis time (delta t) and the ON-rate at which myosin heads enter into the working stroke state when they encounter actin (kON); tws approximately 1/kt-delta t-1/kON. kt was estimated from the ATPase rates of the myosin-coated surface during the sliding of actin filaments. delta t has been determined as less than 1/100 per second, kON was estimated by analyzing the movements of very short (40 nm) filaments. The resulting sliding distance during one ATP hydrolysis cycle near zero load was greater than 100 nm, which is about ten times longer than that expected for a single attachment-detachment cycle between an actin and a myosin head. This leads to the conclusion that the coupling between the ATPase and attachment-detachment cycles is not determined rigidly in a one-to-one fashion.
 ...
PMID:Mechanochemical coupling in actomyosin energy transduction studied by in vitro movement assay. 214 98

We have recently demonstrated that K(+)-induced dilation of cerebral resistance-sized vessels has two independent components, only one of which seemed sodium pump dependent. In our current investigation, potassium-induced dilation of spontaneous tone was compared in cerebral arteries from normotensive Wistar-Kyoto rats and age-matched stroke-prone spontaneously hypertensive rats. Branches of the posterior cerebral artery were cannulated and pressurized, and these vessels developed spontaneous tone. After a 5-minute period in K(+)-free physiological saline solution, K+ was increased in 1-mM increments to a final concentration of 15 mM. In the normotensive arteries, K+ concentrations between 0 and 5 mM K+ resulted in dilations that had a transient (sodium pump-dependent) component, and K+ concentrations in excess of 7 mM produced dilations that lacked a transient (sodium pump-independent) component. Similar branches from the hypertensive rat also responded with transient dilations to K+ (less than 5 mM), and these were significantly greater at 3 mM K+. However, the maintained dilations to K+ (greater than 7 mM), noted in preparations from Wistar-Kyoto rats, were absent in seven of eight preparations. Thus, the impaired dilations, in the hypertensive vessels, to K+ described here is a consequence of altered function of some sodium pump-independent component rather than altered Na+,K(+)-ATPase activity.
 ...
PMID:Impaired potassium-induced dilation in hypertensive rat cerebral arteries does not reflect altered Na+,K(+)-ATPase dilation. 217 51

Subarachnoid hemorrhage was produced experimentally in cats by intracisternal injection of non-heparinized autologous arterial blood obtained by cardiac puncture under ketamine and xylazine anesthesia. Cats were sacrificed at varying time intervals between 30 min and 7 days post ictus. Measurements of resting membrane potential were recorded from smooth muscle cells of the basilar artery. These measurements were obtained by impalement from the adventitial surface of isolated but otherwise intact segments of the artery using glass microelectrodes with tip sizes less than 0.1 micron. The resting membrane potential recorded in vitro from animals previously subjected to subarachnoid hemorrhage in vivo was consistently and significantly depolarized when compared to normal controls. This depolarization was present as early as 30 min post ictus. Addition of the cardiac glycoside, ouabain, in a concentration of 10(-5)M depolarized cells from both control and experimental animals. There is a significant electrogenic pump potential contribution to the resting membrane potential of vascular smooth muscle cells. Ouabain is a potent blocker of Na+, K+-ATPase, the enzyme responsible for maintaining the cation electrochemical gradients. The depolarization recorded in these cells following subarachnoid hemorrhage is not, therefore, due to impairment of the electrogenic pump. The significance and implications of these findings are discussed.
Stroke
PMID:Altered membrane properties of cerebral vascular smooth muscle following subarachnoid hemorrhage: an electrophysiological study. I. Changes in resting membrane potential (Em) and effect on the electrogenic pump potential contribution to Em. 241 49

Time-dependent alterations in integrated cardiovascular function were assessed in the streptozotocin-diabetic rat. Hemodynamic measurements in the intact, anesthetized animal revealed significant and progressive reduction in heart rate after 2, 4, and 8 weeks of diabetes. Myocardial contractility (+ dP/dt) and rate of relaxation (-dP/dt) were preserved at 2 weeks, but progressively declined thereafter. Integrative mechanisms maintained mean arterial blood pressure within normal limits at all time points. Pressure was regulated by minimizing cardiac output reduction via slight increases in stroke volume (Starling mechanism) and concomitant small increases in total peripheral resistance. In response to graded isoproterenol infusion and brief, total aortic occlusion, percent increase of heart rate and + dP/dt was maintained despite decrements in absolute values. Reduced peripheral vasodilation resulted in elevated sensitivity of the heart rate-blood pressure relationship during isoproterenol challenge. The -dP/dt was uniformly impaired in diabetic rats during isoproterenol infusion. When given a rapid saline infusion, diabetic hearts appropriately augmented volume output via the Starling mechanism. Initial hemodynamic abnormalities observed in the intact, diabetic rat are consistent with known defects in cardiac adrenergic receptor density, contractile protein ATPase activity, and sarcoplasmic reticulum calcium uptake. However, many cellular and subcellular defects are compensated by integrative hemodynamic mechanisms while latent alterations are observed only in the intact cardiovascular system.
 ...
PMID:Integrative nature and time course of cardiovascular alterations in the diabetic rat. 242 82

We hypothesize that enhanced activity of capillary Na,K-ATPase promotes Na+ influx into the brain and causes early edema formation in focal cerebral ischemia. The pharmacologic suppression of brain capillary Na,K-ATPase as a means to ameliorate edema formation was examined using the middle cerebral artery occlusion model in 36 cats. With the help of a catheter inserted into the middle cerebral artery, the ischemic brain area was directly perfused with 10(-5) M ouabain. Perfusion was maintained as intermittent 15-second pulse injections given every 5 (n = 6) or 2 (n = 6) minutes. By this method, the naturally occurring circulatory conditions during ischemia were not altered. Four hours after ischemia, the cortical specific gravity at each of six locations over the ischemic area was compared with the corresponding ischemic blood flow measured by the H2 clearance technique. The results show that ouabain perfused every 2 minutes significantly ameliorated edema formation compared with six control cats perfused with Krebs-Ringer solution. In a separate series of experiments, the Na+ flux across the blood-brain barrier was studied by injecting 22NaCl together with an intravascular reference (cobalt-57-labeled microspheres 15 microns in diameter) into the ischemic area. The brain uptake index of 22Na was markedly increased in the ischemic cortex of six control cats; ouabain treatment in six cats suppressed the increase of Na+ influx. The results support our hypothesis that brain capillary Na,K-ATPase activity increases during early focal ischemia, leading to enhanced Na+ together with H2O flux across the blood-brain barrier.
Stroke 1989 Sep
PMID:Effect of enhanced capillary activity on the blood-brain barrier during focal cerebral ischemia in cats. 247 24

The hemodynamic response to maximal exercise was determined in sedentary and trained rats with a chronic myocardial infarction (MI) produced by coronary artery ligation and in rats that underwent sham operations (SHAM). Infarct size in the MI groups of rats comprised 28-29% of the total left ventricle and resulted in both metabolic and hemodynamic changes that suggested that these animals had moderate compensated heart failure. The training regimen used in the present study produced significant increases in maximal O2 uptake (VO2max) when expressed in absolute terms (ml/min) or when normalized for body weight (ml.min-1.kg-1) and consisted of treadmill running at work loads that were equivalent to 70-80% of the animal's VO2max for a period of 60 min/day, 5 days/wk over an 8- to 10-wk interval. This training paradigm produced two major cardiocirculatory adaptations in the MI rat that had not been elicited previously when using a training paradigm of a lower intensity. First, the decrement in the maximal heart rate response to exercise (known as "chronotropic incompetence") found in the sedentary MI rat was completely reversed by endurance training. Second, the downregulation of cardiac myosin isozyme composition from the fast ATPase V1 isoform toward the slower ATPase (V2 and V3) isoforms in the MI rat was partially reversed by endurance training. These cardiac adaptations occurred without a significant increase in left ventricular pump function as an increase in maximal cardiac output (Qmax) and maximal stroke volume (SVmax) did not occur in the trained MI rat.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Cardiac adaptations to endurance training in rats with a chronic myocardial infarction. 252 73


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>