The role of myocardial glycogen content for the development of isoprenaline-induced myocardial lesions in different inbred strains of rats

Abstract

Two inbred rat strains, differing in their resistance to the induction of myocardial lesions by the administration of isoprenaline (ISO), have been developed. The extent of ISO-induced myocardial lesions (IML) was three to five times lower in the ISO-resistant (IR) strain as compared to that in the ISO-sensitive (IS) strain. The two strains differ also in a number of other genetically determined features, e.g., a higher myocardial glycogen content (MGC) and higher adipose tissue weight in IR rats. Between IML extent and MGC a significant negative correlation has been demonstrated in 2nd filial generation of IR and IS hybrids. By contrast, no correlation has been found between the resistance to the development of IML and the other genetically determined features studied. High resistance to the development of IML and a high MGC were also noted in another inbred strain, the hypertriacylglycerolemic (HTG) rats. Comparison of IML extent in HTG, IR and IS rats has revealed that the extent of IML, while depending on MGC, is independent of triacylglycerolemia. MGC can be raised in IR and IS rats by various interventions (e.g., repeated administration of ISD or fasting). Regardless of the intervention used, it entails a simultaneous increase in resistance to the development of IML. In vivo administration of glucose and insulin, however, exerts only a minimal effect on MGC and on the extent of IML. It may be concluded, therefore, that under our experimental conditions the enhanced resistance to the development of IML, whether genetically determined (IR, HTG rats) or induced by some interventions (fasting, repeated ISO administration), is closely related to an increased MGC.

The Influence of Repeated Prestressors on Single Stress Response in Rats

“…Repeated catecholamine administration decreased the capacity of binding catecholamines and lowered the density of receptors (Gudbjarnason & Benediktsdottir 1996). Mráz et al (1995) demonstrated a significant increase in heart glycogen after daily injection of isoprenaline. Other papers (Faltová et al 1983a & b;Mráz et al 1986) demonstrated that a long administration of prolonged stressors like starvation also led to an increase of glycogen and decrease of cardiac damage.…”

“…Heart lesions after 1 mg ¡ kg ª1 of isoprenaline (accumulation index of 203 Hg) more less Mráz et al (1986) Heart lesions after water immersion restraint stress (accumulation index of 203 Hg) more less Starec et al (1994) Gastric ulcers after water immersion restraint stress (ulcer index) less more Starec et al (1994) Heart glycogen less more Mráz et al (1995) Severity of adjuvant arthritis less more Starec et al (1994) Open field -walking less more Rasková et al (1996) Open field -freezing more less Rasková et al (1996) Aggressive behaviour -intruder test less more Starec et al (1994) behavioural and pathophysiological differences observed were established repeatedly during different seasons of the year (Mráz et al 1995;Rasková et al 1996;Starec et al 1996).…”

The potential benefits of a garlic and hydrochlorothiazide combination as antihypertensive and cardioprotective in rats

“…Since 10% fructose in fluid was used for only 6 weeks in our study, we felt it worthwhile to induce myocardial damage by using the cardiotoxic agent ISO without waiting for development of myocardial infarction, which may develop upon extended administration of high fructose intake. ISO induces myocardial damage by various mechanisms such as myocardial hypoperfusion [25], glycogen depletion [26,27], electrolyte imbalance [28], lipid accumulation [29], lipid peroxidation [30] and free radical damage [31]. Since excessive stimulation of b 3 receptors induced thermogenesis [32], animals were maintained under cold conditions to prevent death of the animals due to hyperthermia and respiratory failure.…”

Pharmacodynamic and Pharmacokinetic Interactions of Propranolol with Garlic (Allium sativum) in Rats

“…The combined therapy also attenuated the ISO-mediated cardiac β 1 -receptors excessive stimulation [49], thermogenesis [50], myocardial hypoperfusion [51], glycogen depletion [52], electrolyte imbalance [53], lipid accumulation [54], lipid peroxidation [54], electrocardiographic disturbances [26] and free radical damage [55]. Therefore, it is possible that GH acts by enhancing the endogenous antioxidant defense system and PRO by curtailing the oxidative free radical generation, may maintain the myocardial membrane integrity and thus prevent cardiac dysfunction and hypertension.…”