Abstract
Teleost fish are often regarded with interest for the remarkable ability of several species to tolerate even dramatic stresses, either internal or external, as in the case of fluctuations in O2 availability and temperature regimes. These events are naturally experienced by many fish species under different time scales, but they are now exacerbated by growing environmental changes. This further challenges the intrinsic ability of animals to cope with stress. The heart is crucial for the stress response, since a proper modulation of the cardiac function allows blood perfusion to the whole organism, particularly to respiratory organs and the brain. In cardiac cells, key signalling pathways are activated for maintaining molecular equilibrium, thus improving stress tolerance. In fish, the nitric oxide synthase (NOS)/nitric oxide (NO) system is fundamental for modulating the basal cardiac performance and is involved in the control of many adaptive responses to stress, including those related to variations in O2 and thermal regimes. In this review, we aim to illustrate, by integrating the classic and novel literature, the current knowledge on the NOS/NO system as a crucial component of the cardiac molecular mechanisms that sustain stress tolerance and adaptation, thus providing some species, such as tolerant cyprinids, with a high resistance to stress.
Highlights
Living organisms are constantly exposed to stress
The nitric oxide synthase (NOS)/nitric oxide (NO) system will be discussed as a crucial component of the molecular mechanisms that shape the stress response of the fish heart, in species characterized by a high adaptive flexibility, as in the case of cyprinids (Figure 1)
A significant reduction of the myocardial sensitivity to stretch is observed, if NO is removed from the tissue by PTIO and if soluble guanylate cyclase (sGC) is inhibited by ODQ
Summary
Living organisms are constantly exposed to stress. After Seyle’s definition of stress as “the non-specific response of the body to any demand placed upon it” and the consequent declinations of the different degrees of responses from eustress to distress [1,2], decades of research have established that the ability to face stress-dependent challenges represents a basic mechanism to maintain organism homeostasis. O2 limitations and temperature variations, used as examples of the large variety of challenges that animals are naturally required to face In this context, the nitric oxide synthase (NOS)/nitric oxide (NO) system will be discussed as a crucial component of the molecular mechanisms that shape the stress response of the fish heart, in species characterized by a high adaptive flexibility, as in the case of cyprinids (Figure 1). NOSs are detected in the ventricular visceral pericardium (i.e., epicardium), suggesting that this tissue is a source of nitrergic signalling This extensive intracardiac expression of NOSs isoforms has been considered indicative of the ability of NO to interact with a number of cellular targets to achieve a spatio-temporal modulation of the cardiac function in short- and long-term responses, under basal conditions and in the presence of physical and chemical stimulation [21,30]. It has been proposed that, in the icefish, the reduction of NO2 to NO occurs through cardiac Mb that in this fish may represent the predominant form of NO2 reductase [41]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
