scholarly journals Gradual increase vs. constant-intensity shock during rabbit heart rate conditioning

1976 ◽  
Vol 7 (3) ◽  
pp. 292-294 ◽  
Author(s):  
Arthur L. Yehle ◽  
Hsiu-Ying Lai
Keyword(s):  
Heart Rate ◽  
Gradual Increase ◽  
Rabbit Heart ◽  
Constant Intensity ◽  
Heart Rate Conditioning

Destruction of neurons in the VPM thalamus prevents rabbit heart rate conditioning

1995 ◽  
Vol 57 (1) ◽  
pp. 159-163 ◽  
Author(s):  
Philip M. McCabe ◽  
Matthew D. McEchron ◽  
Edward J. Green ◽  
Neil Schneiderman
Keyword(s):  
Heart Rate ◽  
Rabbit Heart ◽  
Heart Rate Conditioning

β-adrenergic manipulation in amygdala central n. alters rabbit heart rate conditioning

1980 ◽  
Vol 12 (3) ◽  
pp. 419-426 ◽  
Author(s):  
Michela Gallagher ◽  
Bruce S. Kapp ◽  
Robert C. Frysinger ◽  
Peter R. Rapp
Keyword(s):  
Heart Rate ◽  
Rabbit Heart ◽  
Heart Rate Conditioning

Air puff versus shock unconditioned stimuli in rabbit heart rate conditioning

1992 ◽  
Vol 51 (1) ◽  
pp. 195-199 ◽  
Author(s):  
Matthew D. McEchron ◽  
Philip M. McCabe ◽  
Edward J. Green ◽  
Maria M. Llabre ◽  
Neil Schneiderman
Keyword(s):  
Heart Rate ◽  
Rabbit Heart ◽  
Heart Rate Conditioning

Nonlinear dynamics of heart rate variability during experimental hemorrhage in ketamine-anesthetized rats

2000 ◽  
Vol 279 (4) ◽  
pp. H1669-H1678 ◽  
Author(s):  
James E. Skinner ◽  
Brian A. Nester ◽  
William C. Dalsey
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Dimensional Reduction ◽  
Deterministic Model ◽  
Rabbit Heart ◽  
Model System ◽  
Autonomic Response ◽  
Defensive Reaction ◽  
Arrhythmic Death ◽  
System Variables

Indexes of heart rate variability (HRV) based on linear stochastic models are independent risk factors for arrhythmic death (AD). An index based on a nonlinear deterministic model, a reduction in the point correlation dimension (PD2 i), has been shown in both animal and human studies to have a higher sensitivity and specificity for predicting AD. Dimensional reduction subsequent to transient ischemia was examined previously in a simple model system, the intrinsic nervous system of the isolated rabbit heart. The present study presents a new model system in which the higher cerebral centers are blocked chemically (ketamine inhibition of N-methyl-d-aspartate receptors) and the system is perturbed over a longer 15-min interval by continuous hemorrhage. The hypothesis tested was that dimensional reduction would again be evoked, but in association with a more complex relationship between the system variables. The hypothesis was supported, and we interpret the greater response complexity to result from the larger autonomic superstructure attached to the heart. The complexities observed in the nonlinear heartbeat dynamics constitute a new genre of autonomic response, one clearly distinct from a hardwired reflex or a cerebrally determined defensive reaction.

Relation of coronary flow to oxygen supply

1960 ◽  
Vol 199 (1) ◽  
pp. 179-182 ◽  
Author(s):  
Abraham Guz ◽  
George S. Kurland ◽  
A. Stone Freedberg
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Oxygen Content ◽  
Coronary Flow ◽  
Constant Pressure ◽  
Rabbit Heart ◽  
Hemoglobin Solution ◽  
Oxygen Capacity ◽  
Locke Solution ◽  
Solution Change

Coronary flow, heart rate, myocardial oxygen consumption and Walton strain gauge tension were determined in the isolated rabbit heart perfused with hemoglobin solutions of varying oxygen content. Perfusion was carried out under constant pressure and with the hemoglobin solution in equilibrium with 3% CO2 and 97% air under atmospheric tension. Oxygen content was varied from 2 to 18 vol. % by diluting hemoglobin with Ringer-Locke solution. Change from a higher to lower oxyhemoglobin concentration resulted in increased coronary flow; the reserve led to decreased flow. Heart rate, myocardial tension and oxygen consumption were constant at oxygen capacity above 2 vol. %.

scholarly journals Cardiac parameters during the estrous cycle of canine bitches

2017 ◽  
Vol 37 (3) ◽  
pp. 295-299 ◽  
Author(s):  
Rute C.A. de Souza ◽  
Regiane Peres ◽  
Marlos G. Sousa ◽  
Aparecido A. Camacho
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Nervous System ◽  
Estrous Cycle ◽  
Cardiac Rhythm ◽  
Gradual Increase ◽  
Maximal Heart Rate ◽  
Group I ◽  
Mean Heart Rate ◽  
Prospective Investigation

ABSTRACT: The cardiovascular parameters of canine bitches were assessed during the estrous cycle. A total of eleven mongrel female dogs were enrolled in a longitudinal prospective investigation. Six animals were bred during the study and were assigned into group I, in which evaluations were performed during proestrus, estrus, gestational diestrus and anestrus. The five remaining bitches were not bred and underwent evaluations during proestrus, estrus, nongestational diestrus and anestrus. The holter data showed a gradual increase in the minimum and mean heart rate along pregnancy, as well as a reduction during anestrus, which differed significantly among the distinct periods. The values for maximal heart rate documented during pregnancy were significantly lower than those recorded during anestrus, and a variation in the heart rate circadian rhythm was also found, as demonstrated by decreases at night and rises during the day. Cardiac rhythm had a similar performance in both pregnancy and anestrus. Likewise, the blood pressure, electrocardiography, and echocardiography data did not vary during the estrous cycle. The results support the role played by the autonomic nervous system during these two distinct periods in order to attain a heart rate that provides the blood needed by the female’s body during the various stages of the reproductive cycle. Further studies are needed to better clarify the cardiovascular compensatory neuroendocrine events that accompany gestation in this species.

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