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At least 1,171 records · Page 65Linked to original sources
PubMed1999

Store-operated cation channels in the heart and cells of the cardiovascular system.

In many nonexcitable cells, activation of phospholipase C (PLC)-linked receptors results in a release of Ca(2+) from intracellular stores followed by a transmembrane Ca(2+) entry. This Ca(2+) entry underlies the sustained phase of [Ca(2+)](i) increase, is important for various cellular functions including gene expression, secretion and cell proliferation, and is supported by agonist-activated Ca(2+)-permeable ion channels. Ca(2+)-permeable channels which are activated by store depletion and which are therefore referred to as store- operated channels or SOCs form a major pathway for agonist-induced Ca(2+) influx. So far, the molecular structures of these channels have not been identified. Potential candidates are encoded by members of the TRP family, a class of ion channels initially discovered in Drosophila and involved in the PLC-dependent transduction of visual stimuli. Here, we review recent evidence that agonist-induced Ca(2+) influx and especially SOCs are present in different cell types of the heart and of the cardiovascular system and compare these findings with the possible functions and tissue-specific expression of mammalian TRP proteins.

Animals↗
PubMed2006

Role of protein O-linked N-acetyl-glucosamine in mediating cell function and survival in the cardiovascular system.

There is growing recognition that the O-linked attachment of N-acetyl-glucosamine (O-GlcNAc) on serine and threonine residues of nuclear and cytoplasmic proteins is a highly dynamic post-translational modification that plays a key role in signal transduction pathways. Numerous proteins have been identified as targets of O-GlcNAc modifications including kinases, phosphatases, transcription factors, metabolic enzymes, chaperons, and cytoskeletal proteins. Modulation of O-GlcNAc levels has been shown to modify DNA binding, enzyme activity, protein-protein interactions, the half-life of proteins, and subcellular localization. The level of O-GlcNAc is regulated in part by the metabolism of glucose via the hexosamine biosynthesis pathway (HBP), and the metabolic abnormalities associated with insulin resistance and diabetes, such as hyperglycemia, hyperlipidemia, and hyperinsulinemia, are all associated with increased flux through the HBP and elevated O-GlcNAc levels. Increased HBP flux and O-GlcNAc levels have been implicated in the impaired relaxation of isolated cardiomyocytes, blunted response to angiotensin II and phenylephrine, hyperglycemia-induced cardiomyocyte apoptosis, and endothelial and vascular cell dysfunction. In contrast to these adverse effects, recent studies have also shown that O-GlcNAc levels increase in response to acute stress and that this is associated with increased cell survival. Thus, while the relationship between O-GlcNAc levels and cellular function is complex and not well-understood, it is clear that these pathways play a critical role in the regulation of cell function and survival in the cardiovascular system and may be implicated in the adverse effects of metabolic disease on the heart.

Acetylglucosamine↗
PubMed1995

[Role of low-frequency neuronal activity in the medulla in the regulation of the cardiovascular system].

We recorded discharge activity of 45 single neurons located in the rostral ventrolateral medulla (n = 21), lateral tegmental field (n = 10) and caudal raphe (n = 14) nuclei in baroreceptor-denervated decerebrate cats (n = 27). Autoregressive spectral analysis was performed on neuronal activity and systolic arterial pressure (SAP). The discharges of the recorded neurons were correlated to 2- to 6 Hz oscillations or 10 Hz rhythm present in sympathetic neural discharge. A low frequency (LF) oscillation (0.12 +/- 0.02 Hz) was observed in 25 (55%) units. The same rhythmicity was found in SAP variability in 25 of 45 (55%) recordings. In 21 of these cases the LF in SAP variability was highly correlated to LF in neural activity. Moreover, 32 out of 45 (71%) neurons showed a higher rhythm (HF; 0.34 +/- 0.06 Hz) related to the ventilation rate. These data demonstrate the presence of an LF oscillation in the discharge of single medullary neurons, involved in the regulation of cardiovascular system. This LF component was similar to that detectable in the spectral analysis of SAP variability, thus supporting the hypothesis of a central origin of this rhythm, largely independent of baroreceptor input.

Analysis of Variance↗
PubMed1995

[An occupational physiology study at the Asarel Mining and Milling Works--screening for risk factors of the cardiovascular system in workers in an open-pit mine].

It was the purpose of this study to define the frequency of occurrence of a number of individual and occupational factors contributing to development of arterial hypertension in "Asarel" MMW open-pit workers. The investigated subjects numbered 36 and ranged in age from 22 to 55 years (average, 36 +/- 1.9 years). The jobs represented included mainly: diggers, bulldozers, driver, drillers, blasters, road-service workers, electric and mechanic fitters. Endpoints measured and evaluated included: arterial blood pressure, pulse rate, biometric characteristics (age, occupational experience, body height and weight), common risk factors, such as family antecedents, cigarette smoking, alcohol consumption, level of physical activity at and off work, etc. For this sample of open-pit workers, findings indicated a relatively high incidence of hypertension (28% of subjects). The level of arterial hypertension consistently correlated with worker age, length of occupational experience, and body weight. There was high prevalence of cardiovascular risk factors: alcohol consumption, family history, cigarette smoking, use of salty foods, overweight. The observed changes in the cardiovascular system and high prevalence of risk factors point to the necessity of taking specific medical prevention measures. These have been taken into consideration in designing the overall program of upgrading work conditions and organization, as well as improving the style of life of "Asarel" MMW workers.

Adult↗
PubMedDate not supplied

Role of histamine H1-and H2-receptors in the cardiovascular system of the rabbit.

The effects of histamine were examined on the circulation of the blood-perfused heart, kidney, intestine, and hindlimb of rabbits. Single intrarterial injections of drugs were made into the perfusion system of the coronary, renal, mesenteric, or femoral vascular bed. In the hearts, histamine caused dose-dependent positive inotropic and chronotropic responses and vaso-constriction. 2-Methylhistamine, a relatively selective histamine H1-receptor agonist, produced vascular effects very similar to those of histamine, but had no cardiac actions at low and negative inotropic responses at high doses. 4-Methylhistamine, a relatively selective histamine H2-receptor agonist, induced slight vasodilatation and positive inotropic and chronotropic responses. In the renal, mesenteric, and femoral vascular beds, histamine and 2-methylhistamine caused vasoconstriction, while 4-methylhistamine induced slight vasodilatation. Mepyramine, a selective H1-receptor antagonist, blocked the vasoconstriction in response to histamine and 2-methylhistamine, but not the positive inotropic and chronotropic responses to histamine. The combined action of mepyramine and cimetidine (a selective H2-receptor antagonist) eliminated all cardiac and vascular effects of histamine. These results strongly support the view that in the cardiovascular system of the rabbit, H1-receptors mediate negative inotropic effects and vasoconstriction, whereas H2-receptors are responsible for positive inotropic and chronotropic effects and vasodilatation.

Animals↗
PubMed2007

Fetal body weight and the development of the control of the cardiovascular system in fetal sheep.

Reduced birth weight predisposes to cardiovascular diseases in later life. We examined in fetal sheep at 0.76 (n = 18) and 0.87 (n = 17) gestation whether spontaneously occurring variations in fetal weight affect maturation of autonomic control of cardiovascular function. Fetal weights at both gestational ages were grouped statistically in low (LW) and normal weights (NW) (P < 0.01). LW fetuses were within the normal weight span showing minor growth dysproportionality at 0.76 gestation favouring heart and brain, with a primary growth of carcass between 0.76 and 0.87 gestation (P < 0.05). While twins largely contributed to LW fetuses, weight differences between singletons and twins were absent at 0.76 and modest at 0.87 gestation, underscoring the fact that twins belong to normality in fetal sheep not constituting a major malnutritive condition. Mean fetal blood pressure (FBP) of all fetuses was negatively correlated to fetal weight at 0.76 but not 0.87 gestation (P < 0.05). At this age, FBP and baroreceptor reflex sensitivity were increased in LW fetuses (P < 0.05), suggesting increased sympathetic activity and immaturity of circulatory control. Development of vagal modulation of fetal heart rate depended on fetal weight (P < 0.01). These functional associations were largely independent of twin pregnancies. We conclude, low fetal weight within the normal weight span is accompanied by a different trajectory of development of sympathetic blood pressure and vagal heart rate control. This may contribute to the development of elevated blood pressure in later life. Examination of the underlying mechanisms and consequences may contribute to the understanding of programming of cardiovascular diseases.

Animals↗
PubMed1997

Function, regulation, pharmacology, and molecular structure of ATP-sensitive K+ channels in the cardiovascular system.

ATP-sensitive K+ (K[ATP]) channels are inhibited by intracellular ATP and activated by intracellular nucleoside diphosphates, and thus provide a link between cellular metabolism and excitability. K(ATP) channels are widely distributed in various tissues and may be associated with diverse cellular functions. In the heart, the K(ATP) channel appears to be activated during ischemic or hypoxic conditions and may be responsible for the increase of K+ efflux and shortening of the action potential duration. Therefore, opening of this channel may result in cardioprotective as well as proarrhythmic effects. In the vascular smooth muscle, the K(ATP) channel is believed to mediate the relaxation of vascular tone. Thus, K(ATP) channels play important regulatory roles in the cardiovascular system. Furthermore, K(ATP) channels are the targets of two important classes of drugs, i.e., the antidiabetic sulfonylureas, which block the channels, and a series of vasorelaxants called "K+ channel openers," which tend to maintain the channels in an open conformation. Recently, the molecular structure of K(ATP) channels has been clarified. The K(ATP) channel in pancreatic beta-cells is a complex composed of at least two subunits, a member of inwardly rectifying K+ channels and a sulfonylurea receptor. Subsequently, two additional homologs of the sulfonylurea receptor, which form cardiac and smooth muscle type K(ATP) channels, respectively, have been reported. Further works are now in progress to understand the molecular mechanisms of K(ATP) channel function.

Adenosine Triphosphate↗
PubMed1986

Role of intracerebral angiotensin receptors in the regulation of vasopressin release and the cardiovascular system.

In order to investigate the physiological role of the brain renin-angiotensin system in the regulation of vasopressin (ADH) release, angiotensin II (Ang II, 10 ng/kg/min) or 1-Sar-8-Ile-Ang II (50 ng/kg/min), an Ang II antagonist, was administered intracerebroventricularly to dogs (n = 42) anesthetized with urethane and chloralose after morphine sedation. The effects of the intravenous infusion of either 0.15 M or 2.5 M NaCl (0.1 ml/kg/min, 75 min) were also studied. In control dogs, artificial cerebrospinal fluid (ACSF) was administered at a rate of 10 microliter/min for 105 min. ACSF given intracerebroventricularly plus 0.15 M NaCl given intravenously did not affect ADH release, but 2.5 M NaCl given intravenously raised the plasma ADH level in parallel with the rise in plasma osmolality. Heart rate and blood pressure did not change significantly in ACSF along with 0.15 M NaCl, but heart rate increased significantly in ACSF along with 2.5 M NaCl. Ang II along with 0.15 M NaCl significantly raised plasma ADH and decreased heart rate without any changes in blood pressure. Ang II along with 2.5 M NaCl brought about a significant rise in plasma ADH level, arterial blood pressure, heart rate, and plasma osmolality. But simultaneous application of Ang II and 2.5 M NaCl did not result in a larger rise in plasma ADH than that expected from the effects of the two stimulations given separately. Namely, Ang II did not potentiate ADH release elicited by osmotic stimulation. Ang II antagonist given intracerebroventricularly neither affected ADH release and the cardiovascular system in 0.15 M NaCl nor inhibited ADH release in response to osmotic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1995

[Corrected QT interval and diabetic neuropathy of the cardiovascular system].

UNLABELLED: Our objective was the analysis of the utility of the corrected QT interval (QTc) for the assessment of severity of cardiac autonomic neuropathy. Fourty nine patients with insulin-dependent diabetes mellitus/IDDM/were enrolled in the study. Their ages ranged between 16 and 58 years, and the duration of IDDM ranged between 1 and 38 years. Patients were tested for cardiac autonomic neuropathy using ProSciCard system. We carried out four tests: resting pulse deep breathing pulse Ewing test Valsalva maneuver Our results showed the relationship between the QTc interval lengthening and the occurance of cardiac autonomic neuropathy. No correlation was found between the QTc interval and the extend of cardiac autonomic neuropathy. CONCLUSIONS: The QTc interval measurement is a good routine test for the diagnosis of cardiac autonomic neuropathy. The corrected QT interval is not a reliable indicator of the extend of cardiac autonomic neuropathy.

Adolescent↗