scholarly journals Doxapram Hydrochloride Aggravates Adrenaline-Induced Arrhythmias Accompanied by Bidirectional Ventricular Tachycardia

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Shota Oikawa ◽  
Hiroko Nomura ◽  
Miki Nishio ◽  
Rina Nagata ◽  
Tadayoshi Hata
Keyword(s):  
Ventricular Tachycardia ◽  
Wistar Rats ◽  
Inhibitory Effect ◽  
Myocardial Cells ◽  
Drug Induced ◽  
Genetic Abnormalities ◽  
Female Wistar Rats ◽  
Intracellular Ca ◽  
Respiratory Stimulant ◽  
Arrhythmogenic Effects

Objectives. Doxapram hydrochloride is a respiratory stimulant that has an inhibitory effect on myocardial IK1 potassium channels and is thought to increase membrane instability and excitability in myocardial cells. We examined the arrhythmogenic effects of doxapram hydrochloride in a rat model of halothane adrenaline-induced arrhythmia. Methods. Thirteen female Wistar rats (12–14 weeks old) were used in the study. Animals were anesthetized with inhalation of halothane to permit observation of the effects of doxapram hydrochloride on halothane adrenaline-induced arrhythmia. Time-dependent changes in ECG repolarization characteristics (QT, QTc, JTp, JT, and Tp-e intervals) were studied. Results. Doxapram hydrochloride itself did not induce arrhythmia but did induce bidirectional ventricular tachycardia after addition of adrenaline. Conclusion. Drug-induced impairment of intracellular Ca2+ regulation caused BVT in the absence of genetic abnormalities in proteins in the sarcoplasmic reticulum.

Caffeine-induced arrhythmias in murine hearts parallel changes in cellular Ca2+ homeostasis

2005 ◽  
Vol 289 (4) ◽  
pp. H1584-H1593 ◽  
Author(s):  
Richard Balasubramaniam ◽  
Sangeeta Chawla ◽  
Andrew A. Grace ◽  
Christopher L.-H. Huang
Keyword(s):  
Heart Failure ◽  
Electrical Stimulation ◽  
Ventricular Tachycardia ◽  
Stimulation Protocol ◽  
Programmed Electrical Stimulation ◽  
Intact Mouse ◽  
Fluorescence Measurements ◽  
Ventricular Cells ◽  
Intracellular Ca ◽  
Arrhythmogenic Effects

Heart failure leading to ventricular arrhythmogenesis is a major cause of clinical mortality and has been associated with a leak of sarcoplasmic reticular Ca2+ into the cytosol due to increased open probabilities in cardiac ryanodine receptor Ca2+-release channels. Caffeine similarly increases such open probabilities, and so we explored its arrhythmogenic effects on intact murine hearts. A clinically established programmed electrical stimulation protocol adapted for studies of isolated intact mouse hearts demonstrated that caffeine (1 mM) increased the frequency of ventricular tachycardia from 0 to 100% yet left electrogram duration and latency unchanged during programmed electrical stimulation, thereby excluding slowed conduction as a cause of arrhythmogenesis. We then used fluorescence measurements of intracellular Ca2+ concentration in isolated mouse ventricular cells to investigate parallel changes in Ca2+ homeostasis associated with these arrhythmias. Both caffeine (1 mM) and FK506 (30 μM) reduced electrically evoked cytosolic Ca2+ transients yet increased the frequency of spontaneous Ca2+-release events. Diltiazem (1 μM) but not nifedipine (1 μM) pretreatment suppressed these increases in frequency. Identical concentrations of diltiazem but not nifedipine correspondingly suppressed the arrhythmogenic effects of caffeine in whole hearts. These findings thus directly implicate spontaneous Ca2+ waves in triggered arrhythmogenesis in intact hearts.

NEW DATA CONCERNING THE ROLE PLAYED BY PROGESTERONE IN THE CONTROL OF FOLLICULAR GROWTH IN THE RAT

1974 ◽  
Vol 75 (3) ◽  
pp. 569-578 ◽  
Author(s):  
G. Buffler ◽  
S. Roser
Keyword(s):  
Wistar Rats ◽  
Venous Blood ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Cycle Duration ◽  
Follicular Growth ◽  
The Third ◽  
Female Wistar Rats

ABSTRACT The mechanisms involved in the prolongation of the oestrous cycle following LH administration were studied in 4-day cyclic female Wistar rats. In females injected with LH on the morning of dioestrus I there was an increase in ovarian venous blood progesterone as compared with non-injected animals. In both LH-treated females, and those injected with progesterone on the morning of dioestrus I, a slowing up in follicular growth was observed from the afternoon of dioestrus I. The size of follicles greater than 400 urn present in LH or progesterone injected animals on the third day of cycle was similar to the size reached by the same range of follicles in non-injected animals on the second day of the cycle. Hence, the increase in endogenous ovarian progesterone elicited by LH was considered as the cause of the slowing up of follicular growth and therefore of the lengthening of the oestrous cycle duration in female rats injected with LH at the beginning of 4-day cycle.

Oral in vivo Bactofection in Dextran Sulfate Sodium Treated Female Wistar Rats

2010 ◽  
Vol 58 (3) ◽  
pp. 171-176 ◽  
Author(s):  
Roland Pálffy ◽  
Michal Behuliak ◽  
Roman Gardlík ◽  
Peter Jáni ◽  
L'udevít Kádaši ◽  
...  
Keyword(s):  
Wistar Rats ◽  
Dextran Sulfate ◽  
Dextran Sulfate Sodium ◽  
Female Wistar Rats

scholarly journals The fertility assessment of normal cyclic Wistar rats following the administration of methanolic extract of Portulaca oleracea: an experimental study

2021 ◽  
Vol 26 (1) ◽  
Author(s):  
Izuchukwu Azuka Okafor ◽  
Uchenna Somtochukwu Nnamah ◽  
Jude Nnaka
Keyword(s):  
Estrous Cycle ◽  
Adult Female ◽  
Wistar Rats ◽  
Major Effect ◽  
Reproductive Hormones ◽  
Portulaca Oleracea ◽  
High Dose ◽  
Methanolic Extracts ◽  
Cycle Arrest ◽  
Female Wistar Rats

Abstract Background Purslane is a widely distributed shrub used for the treatment of different ailments. The increasing reproductive complications associated with herbal treatments have led to the need to critically evaluate the safety and/or reproductive potentials of commonly used plant extracts. This study investigated the reproductive effect of methanolic extracts of Portulaca oleracea (MEPO) in adult female Wistar rats. Results Group C showed a significant decrease both in relative ovarian weight (p = 0.000), and relative uterine weight (p = 0.037), when compared with the control. There were no significant (p ˃ 0.05) changes in the levels of follicle-stimulating hormone, luteinizing hormone, progesterone, and estradiol. When compared to the control, groups B and C showed abnormal estrous cycle and cycle arrest especially at the metestrus phase with mild congestion of a few blood vessels in the ovary and uterus. Conclusions MEPO may possess some anti-fertility effect, as it disrupts the estrous cycle of adult female Wistar rats; although it has no major effect on the reproductive hormones, uterus, and ovarian histology of adult female Wistar rats. However, high dose consumption should be taken with precaution.

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