Ameliorative Effect of Ascorbic Acid and Glutathione in Combating the Cryoinjuries During Cryopreservation of Exotic Jack Semen.

The present study was designed to study the adverse effects of cryopreservation and evaluation of the cryoprotective effect of reduced glutathione (GSH) and ascorbic acid (AA) supplementation on exotic jack semen in combination or alone. For this, 24 semen samples from four adult and fertile jacks were collected via artificial vagina using an estrus jenny as dummy. After semen collection, the semen was evaluated for various qualitative and quantitative parameters in fresh, cooled, and frozen-thawed semen.

Role of NADPH oxidase and xanthine oxidase in mediating inducible VT/VF and triggered activity in a canine model of myocardial ischemia.

Background: Ventricular tachycardia or fibrillation (VT/VF) of focal origin due to triggered activity (TA) from delayed afterdepolarizations (DADs) is reproducibly inducible after anterior coronary artery occlusion. Both VT/VF and TA can be blocked by reducing reactive oxygen species (ROS). We tested the hypothesis that inhibition of NADPH oxidase and xanthine oxidase would block VT/VF.

Association among intracardiac T-wave alternans, ischemia, and spontaneous ventricular arrhythmias after coronary artery occlusion in a canine model.

T-wave alternans (TWA) has been investigated as a marker for susceptibility to lethal ventricular arrhythmia. In this article, we studied intracardiac TWA and ischemia as predictors of spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) in a canine model of coronary artery occlusion (CAO). Anesthetized, open-chest dogs were studied.

Catecholamine-independent heart rate increases require Ca2+/calmodulin-dependent protein kinase II.

Background: Catecholamines increase heart rate by augmenting the cAMP-responsive hyperpolarization-activated cyclic nucleotide-gated channel 4 pacemaker current (I(f)) and by promoting inward Na(+)/Ca(2+) exchanger current (I(NCX)) by a "Ca(2+) clock" mechanism in sinoatrial nodal cells (SANCs). The importance, identity, and function of signals that connect I(f) and Ca(2+) clock mechanisms are uncertain and controversial, but the multifunctional Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is required for physiological heart rate responses to β-adrenergic receptor (β-AR) stimulation. The aim of this study was to measure the contribution of the Ca(2+) clock and CaMKII to cardiac pacing independent of β-AR agonist stimulation.

I(f) and SR Ca(2+) release both contribute to pacemaker activity in canine sinoatrial node cells.

Increasing evidence suggests that cardiac pacemaking is the result of two sinoatrial node (SAN) cell mechanisms: a 'voltage clock' and a Ca(2+) dependent process, or 'Ca(2+) clock.' The voltage clock initiates action potentials (APs) by SAN cell membrane potential depolarization from inward currents, of which the pacemaker current (I(f)) is thought to be particularly important. A Ca(2+) dependent process triggers APs when sarcoplasmic reticulum (SR) Ca(2+) release activates inward current carried by the forward mode of the electrogenic Na(+)/Ca(2+) exchanger (NCX).

Angiotensin II effects on ischemic focal ventricular tachycardia are predominantly mediated through myocardial AT(2) receptor.

Ischemic focal ventricular tachycardia (VT) occurs in animals and humans. Angiotensin-converting enzyme inhibitors and receptor blockers reduce sudden death in patients with ischemic heart disease. In our dog model of coronary artery occlusion (CAO), we tested the hypothesis that angiotensin II (AGII) will selectively promote focal VT and that the specific AT(2) blocker PD-123319 (PD), or AT(1) blocker losartan, will affect this VT.

Free radical scavenger specifically prevents ischemic focal ventricular tachycardia.

Background: Focal ventricular tachycardia (VT) in acute myocardial ischemia is closely related to triggered activity (TA), which may be blocked by scavenging reactive oxygen species (ROS).

Objective: This study analyzed effects of acutely administered ROS scavenger-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) on VT in vivo and TA in vitro.

Methods: Forty-three alpha chloralose anesthetized dogs with coronary artery occlusion were studied.

Rapunzel syndrome reviewed and redefined.

Rapunzel syndrome is a rare presentation of a trichobezoar, with 24 cases having been reported in literature so far. This syndrome has been reported in 23 female and 1 male patient with a mean age of 10.8 years.