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Cardiac Acceleration (cardiac + acceleration)
Selected AbstractsDevelopment of Tactile Responses in Human Preterm and Full-Term Infants From 30 to 40 Weeks Postconceptional AgeINFANCY, Issue 1 2002Isabel Fearon Maturation of tactile sensitivity prior to term was examined in 36 preterm and 13 full-term infants using a fixed-trial, habituation procedure. Each infant was presented with a series of 8 habituation (arm stroke), 2 novel (arm lift), and 2 recovery (arm stroke) stimulus trials while heart rate and body movements were recorded. Maturation was observed with a gradual increase in the magnitude of the stimulus-elicited cardiac acceleration and cardiac-movement coupling from 30 to 40 weeks postconceptional age. The majority of infants displayed habituation,an excitatory response (heart rate acceleration and body movement),to the initial presentation of a tactile stimulus, response decline with repeated stimulations, and renewed response to a novel stimulus. A substantial number of infants (40%) failed to respond initially to the tactile stimulus, increased responding over several stimulus presentations, and failed to discriminate the presentation of a novel stimulus. We speculate that these differences in response patterns observed over all ages represent individual difference in the perception of stimulus intensity. [source] RUN/EDIT information processing mode and phasic cardiac accelerationPSYCHOPHYSIOLOGY, Issue 6 2008Tytus Sosnowski Abstract Our previous research showed that tasks demanding running of ready-to-use programs (RUN tasks) caused a greater tonic heart rate increase than did tasks that require problem solving (EDIT tasks). We found also a similar though not so consistent effect in the analysis of phasic cardiac acceleration. The aim of the present study was to replicate the last finding using new experimental tasks. Fifty-four male secondary school pupils were divided randomly into three experimental groups. Each group performed a different version of a nonsignaled reaction time (RT) task: simple RT, sensory choice RT, and semantic choice RT. Participants had to respond within an established time limit, but this limit was continuously modified in such a way that each participant was given positive feedback in approximately 50% of trials. According to expectations, the simple RT task evoked greater phasic cardiac acceleration than did the choice RT tasks. [source] Development of the Thyroid Hormone Receptor ,-Subtype Agonist KB-141 : A Strategy for Body Weight Reduction and Lipid Lowering with Minimal Cardiac Side EffectsCARDIOVASCULAR THERAPEUTICS, Issue 2 2005Gary J. Grover ABSTRACT Few treatments for obesity exist and improvements for treatment of hyperlipidemia are still desirable. Thyroid hormone receptors (TRs) regulate body weight, adiposity, and cholesterol levels. However, thyroid hormones can have deleterious effects, particularly cardiac acceleration, that limits the use of hormones in the treatment of obesity. There is evidence that the TR, subtype mediates lowering of blood cholesterol levels and possibly elevation of metabolic rate, whereas TR, appears to control heart rate. In studies, described in this review article, we examined the effects of selective TR, activation on metabolic rate and heart rate in mice, rats and monkeys. T3 had a greater effect on increasing heart rate in wild type (WT) than in TR,-/- mice (ED15 values of 34 and 469 nmol/kg/day, respectively). T3 increased metabolic rate (MVO2) in both WT and TR,-/- mice, but the effect on TR,-/- mice was less pronounced compared to WT mice. Stimulation of MVO2 is mediated by both TR, and TR,, but with different profiles. In cholesterol-fed rats, KB-141, a selective TR, agonist, increased MVO2 with a 10-fold selectivity and lowered cholesterol with a 27-fold selectivity vs. tachycardia. In primates, KB-141 caused significant, cholesterol, Lp(a) and body weight reduction after 1 week of treatment with no effect on heart rate. These data suggest that selective TR, agonists may represent a novel class of drugs for the treatment of obesity, hypercholesterolemia and elevated Lp(a), which may make them useful therapeutics for patients with metabolic syndrome. [source] DUAL ACTIVATION OF CARDIAC SYMPATHETIC AND PARASYMPATHETIC COMPONENTS DURING CONDITIONED FEAR TO CONTEXT IN THE RATCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2006Pascal Carrive SUMMARY 1The present study investigates the contribution of the sympathetic and vagal parasympathetic systems to the tachycardic response of long-lasting (40 min) conditioned fear responses to context. 2The conditioned fear response evoked by re-exposure to a footshock chamber was tested 10 min after intravenous injection of the ,-adrenoceptor antagonist propranolol (2 mg/kg) or the muscarinic antagonist atropine methyl nitrate (2 mg/kg) in rats implanted with radiotelemetric probes. 3Compared with saline controls, the drugs did not change the behavioural component of the response (freezing, 22 kHz ultrasonic vocalizations) or its pressor component (+28 mmHg). 4Propranolol abolished the tachycardic response of fear, whereas atropine more than doubled it (from +75 to +175 b.p.m. above resting baseline). 5The results demonstrate that both sympathetic and vagal parasympathetic outflows to the heart are strongly activated during conditioned fear. The vagal activation may act to hold back cardiac acceleration while the animal waits for the aversive stimulus to come. [source] | ||||||||||