Elementary properties of cardiac calcium channels: a brief review

This article reviews the new insight into the function of cardiac calcium channels made possible by electrophysiological recordings from single cells and single channels. The unitary properties of the two different types of cardiac calcium channels are discussed and contrasted, and special emphasis is given to the mechanisms of channel permeation, gating, and modulation by exogenous and endogenous ligands.     

Recovery from training: a brief review: brief review

Athletes spend a much greater proportion of their time recovering than they do in training. Yet, much attention has been given to training with very little investigation of recovery. The purpose of this review is to stimulate further research into this vital area of training. Recovery can be categorized in three terms: i) immediate recovery between exertions; ii) short-term recovery between repeats (e.g., between resistance sets or interval bouts); and iii) training recovery between workouts. The focus of this review is training recovery. Full training recovery is essential to optimal performance and improvement. This review includes an examination of extant research on recovery and a very brief review of some potential modalities and techniques for hastening recovery and the time course of recovery and responses to some treatments. Measures of recovery and practical considerations are discussed briefly. Much research is needed in this area, but there are obstacles to high quality research. Attention must be given to key issues in research on recovery, especially the individual response to recovery treatments.     

Myocardial actions of prostaglandins in isolated cat cardiac tissue.

The inotropic responses to prostaglandins (PG) A₁, E₁, E₂ and F_2α were studied in isolated cat myocardial tissue. PGA₁ and F_2α exhibited no significant inotropic effects, whereas, PGE₂ and PGE₁ produced negative inotropic effects at concentrations of 2.8 × 10⁻⁷ and 2.8 × 10⁻⁶ M in isolated cat papillary muscles.In isolated perfused cat hearts, PGE₁ (2.8 × 10⁻⁶M) produced a negative inotropic effect along with a significant increase in coronary flow. As flow declined, the negative inotropic effect became more severe. PGE₁ at 2.8 × 10⁻⁹ M produced a sustained increase in coronary flow and oxygen consumption with no inotropic effect. PGE₂ and F_2α did not exert significant changes in coronary flow or contractile force.Thus prostaglandins do not appear to exert significant positive inotropic effects at physiologic or at generally accepted pharmacologic concentrations in isolated cat heart preparations. At extremely high concentrations, prostaglandins E₁ and E₂ exert a negative inotropic effect; however, this would not explain the protective effect of these prostaglandins in circulatory shock.     

The role of P2X7 receptors in tissue fibrosis: a brief review

Many previous studies have demonstrated that P2X₇ receptors (P2X₇Rs) have a pleiotropic function in different pathological conditions and could represent a novel target for the treatment of a range of diseases. In particular, recent studies have explored the role of P2X₇R in fibrosis, the pathological outcome of most chronic inflammatory diseases. The aim of this review is to discuss the biological features of P2X₇R and summarize the current knowledge about the putative role of the P2X₇R in triggering fibrosis in a wide spectrum of organs such as the lung, kidney, liver, pancreas, and heart.     

Bats and Viruses： a Brief Review

Bats, probably the most abundant, diverse and geographically dispersed vertebrates on earth, have recently been shown to be the reservoir hosts of a number of emerging viruses responsible for severe human and livestock disease outbreaks. Flying foxes have been demonstrated to be the natural reservoir for Hendra and Nipah viruses. Evidence supporting the possibility of bats as potential reservoirs for SARS coronavirus (SARS-CoV) and Ebola virus has also been reported. The recent discovery of these viruses and other viruses occurring naturally in the bat population provides a unique insight into a diverse pool of potentially emergent and pathogenic viruses. The factors which influence the ability of zoonotic viruses to effectively cross the species barrier from bats to other animal populations are poorly understood. A brief review is provided here on the recently emerged bat viruses and on current and future strategies for research in this area.     

Edwardsiellosis in fish: a brief review

Edwardsiellosis is one of the most important bacterial diseases in fish. Scientific work on this disease started more than forty years ago and numerous workers around the world are continually adding to the knowledge of the disease. In spite of this, not a single article that reviews the enormous scientific data thus generated is available in the English language. This article briefly discusses some of the recent research on edwardsiellosis, describing the pathogen’s interaction with the host and environment, its pathogenesis and pathology as well as diagnostic, preventive and control measures.     

Edwardsiellosis in fish: a brief review

Edwardsiellosis is one of the most important bacterial diseases in fish. Scientific work on this disease started more than forty years ago and numerous workers around the world are continually adding to the knowledge of the disease. In spite of this, not a single article that reviews the enormous scientific data thus generated is available in the English language. This article briefly discusses some of the recent research on edwardsiellosis, describing the pathogen's interaction with the host and environment, its pathogenesis and pathology as well as diagnostic, preventive and control measures.     

Autonomic regulation of pacemaker activity: role of heart nitric oxide synthases

In autonomic-blocked rats treated with NG-nitro-L-arginine methyl ester (L-NAME, 7.5 mg/kg), heart rate increased 18% and mean arterial pressure increased 48%. Thyroidectomy, along with autonomic blockade, hampered the chronotropic response but did not modify the effect on blood pressure. After 150 min of autonomic blockade, the experimental end point, total nitric oxide (NO) production by heart NO synthases (NOS) decreased 61%: from 54 to 21 nmol NO.min-1.g heart-1. Mitochondrial NOS (mtNOS) and sarcoplasmic reticulum endothelial NOS activities decreased 74% and 52%, respectively. Mitochondria isolated from whole heart showed a well-coupled oxidative phosphorylation with high respiratory control and ADP-to-O ratios, decreased mtNOS activity (55-60%), and decreased mtNOS protein expression (70%). Immunohistochemistry with anti-inducible NOS antibody linked to gold particles localized mtNOS at the inner mitochondrial membranes. Histochemical right atrial NOS (NADPH-diaphorase) decreased 55% after heart denervation. The effects of autonomic denervation on the NO system were partially prevented by thyroidectomy performed simultaneously with autonomic blockade. Western blot analysis indicated a very rapid mtNOS protein turnover (half time=120 min) with a process of protein expression that was upregulated by thyroidectomy and a degradation process that was downregulated by the autonomic nervous system. The observations suggest that NO-mediated pathways contribute to pacemaker heart activity, likely through the NO steady-state levels in the right atrium and the whole heart.     

Mauthner cell-evoked synaptic actions on pacemaker medullary neurons of a weakly electric fish

The present study was designed to examine the synaptic events in neurons of the pacemaker nucleus of Gymnotus carapo during the increase in rate of the electric organ discharge following activation of Mauthner cells. Pacemaker and relay cells were investigated using intracellular recordings which were performed under two different conditions: (1) with the pacemaker nucleus spontaneously discharging and (2) after its activity was abolished by anesthesia. Mauthner axon activation induced an increase in the rate of pacemaker cell discharges. This response was accompanied by an increase in the slope of the pacemaker potential (up to 110%) and a depolarization of these cells. The discharges of relay cells followed one to one those of pacemaker cells. In contrast to that observed in pacemaker cells, only brief depolarizing antidromic effects could be evoked in relay cells after Mauthner axon activation. In quiescent pacemaker cells, Mauthner cell activation induced a prolonged (up to 500 ms) depolarizing potential with an average amplitude of 1.92 ± 0.82 mV; its latency was 4.43 ± 1.14 ms. Our data indicate that, within the pacemaker nucleus, the population of pacemaker cells is the only target for Mauthner cell-evoked, short-latency excitatory synaptic actions. Accepted: 1 March 1997