Transient inotropic effects of low extracellular sodium in perfused rat heart

Sixty Years of Heart Research in the Institute of Physiology of the Czech Academy of Sciences

In 2023, six decades have elapsed since the first experimental work on the heart muscle was published, in which a member of the Institute of Physiology of the Czech Academy of Sciences participated as an author; Professor Otakar Poupa was the founder and protagonist of this research domain. Sixty years - more than half of the century - is certainly significant enough anniversary that is worth looking back and reflecting on what was achieved during sometimes very complicated periods of life. It represents the history of an entire generation of experimental cardiologists; it is possible to learn from its successes and mistakes. The objective of this review is to succinctly illuminate the scientific trajectory of an experimental cardiological department over a 60-year span, from its inaugural publication to the present. The old truth - historia magistra vitae - is still valid. Keywords: Heart, Adaptation, Development, Hypoxia, Protection.

Complications of fluid overload during hysteroscopic surgery: cardiomyopathy and epistaxis - A case report

Background

Hysteroscopic surgery has been used in various gynecological fields. However, massive fluid overload can occur as a complication due to persistent infusion of media for uterine cavity distension. We present the case of a woman who developed cardiomyopathy with pulmonary edema and epistaxis during hysteroscopic surgery.

Case

A 76-year-old female underwent hysteroscopic septectomy. She manifested abrupt, active nasal bleeding and regurgitation in the intravenous line. Heart rate, SpO₂, and PETCO₂ decreased from 55 beats/min to 29 beats/min, from 100% to 56%, and from 31 mmHg to 9 mmHg, respectively. After the operation, brain CT showed bilateral prominent superior ophthalmic vein dilation. Echocardiography showed left ventricle apical ballooning and global hypokinesia. The patient recovered after two days of conservative management, with no sequelae.

Conclusions

Although hysteroscopic surgery is a simple procedure, careful monitoring is necessary to prevent complications from absorption of fluid distending media during the procedure.

Prevalence and risk factors for postoperative stress-related cardiomyopathy in adults

Stress-related cardiomyopathy can develop during the postoperative period due to surgery-related stress factors. However, the prevalence and risk factors for this condition are not yet known. During a retrospective, observational study, patients older than 19 years who underwent procedures from January 2011 to December 2015 at a tertiary hospital were included. The main aim was to identify the prevalence and related risk factors for postoperative stress-related cardiomyopathy. To estimate the incidence per risk factor, univariate and multivariate Poisson regression analyses were performed. During the 5-year period, 95,840 patients older than 19 years underwent 125,314 procedures, and the prevalence of postoperative stress-related cardiomyopathy was 17.74 per 100,000 (95% confidence interval, 9.31–26.17), with an in-hospital mortality of 23.5%. As a result, three risk factors were significantly associated: preoperative American Society of Anesthesiologists classification (incidence rate ratio, 5.901 for American Society of Anesthesiologists class 1–2 [ref] versus 3–6; 95% confidence interval,1.289–27.002; P = 0.022); preoperative body mass index (incidence rate ratio, 1.247 for increases of 18.5 [ref] to 30; 95% confidence interval, 1.067–1.458; P = 0.006); and preoperative serum sodium (incidence rate ratio, 0.830 for each increase of 10 mmol/L from 130; 95% confidence interval, 0.731–0.942; P = 0.004). The incidence rate ratio for age for each increase of 10 years from 50 years was 1.057, but it was not statistically significant (P = 0.064). Our study found that the prevalence of postoperative stress-related cardiomyopathy was 17.74 patients per 100,000 adult patients over the course of 5 years, with four cases of in-hospital mortality. Factors that increased the risk of postoperative stress-related cardiomyopathy included higher American Society of Anesthesiologists class (≥3), preoperative hyponatremia, and higher preoperative body mass index.

Modification of intracellular calcium concentration in cardiomyocytes by inhibition of sarcolemmal Na+/H+exchanger

Although the Na+/H+exchanger (NHE) is considered to be involved in regulation of intracellular Ca2+concentration ([Ca2+]i) through the Na+/Ca2+exchanger, the exact mechanisms of its participation in Ca2+handling by cardiomyocytes are not fully understood. Isolated rat cardiomyocytes were treated with or without agents that are known to modify Ca2+movements in cardiomyocytes and exposed to an NHE inhibitor, 5-( N-methyl- N-isobutyl)amiloride (MIA). [Ca2+]iin cardiomyocytes was measured spectrofluorometrically with fura 2-AM in the absence or presence of KCl, a depolarizing agent. MIA increased basal [Ca2+]iand augmented the KCl-induced increase in [Ca2+]iin a concentration-dependent manner. The MIA-induced increase in basal [Ca2+]iwas unaffected by extracellular Ca2+, antagonists of the sarcolemmal (SL) L-type Ca2+channel, and inhibitors of the SL Na+/Ca2+exchanger, SL Ca2+pump ATPase and mitochondrial Ca2+uptake. However, the MIA-induced increase in basal [Ca2+]iwas attenuated by inhibitors of SL Na+-K+-ATPase and sarcoplasmic reticulum (SR) Ca2+transport. On the other hand, the MIA-mediated augmentation of the KCl response was dependent on extracellular Ca2+concentration and attenuated by agents that inhibit SL L-type Ca2+channels, the SL Na+/Ca2+exchanger, SL Na+-K+-ATPase, and SR Ca2+release channels and the SR Ca2+pump. However, the effect of MIA on the KCl-induced increase in [Ca2+]iremained unaffected by treatment with inhibitors of SL Ca2+pump ATPase and mitochondrial Ca2+uptake. MIA and a decrease in extracellular pH lowered intracellular pH and increased basal [Ca2+]i, whereas a decrease in extracellular pH, in contrast to MIA, depressed the KCl-induced increase in [Ca2+]iin cardiomyocytes. These results suggest that NHE may be involved in regulation of [Ca2+]iand that MIA-induced increases in basal [Ca2+]i, as well as augmentation of the KCl-induced increase in [Ca2+]i, in cardiomyocytes are regulated differentially.

Alterations in Ca(2+)-channels during the development of diabetic cardiomyopathy

In order to examine the status of Ca2+ channels in heart sarcolemma during the development of diabetes, rats were injected intravenously with 65 mg/kg streptozotocin and hearts were removed 1, 3 and 8 weeks later. Crude membranes from the ventricular muscle were prepared and the specific binding of 3H-nitrendipine was studied by employing different concentrations of this Ca(2+)-antagonist. A significant decrease in both dissociation constant and maximal number of 3H-nitrendipine binding was observed in 3 and 8 weeks diabetic preparations. No such alterations were evident in diabetic brain membranes. Treatment of diabetic animals with insulin prevented the occurrence of these changes in the myocardium. The altered 3H-nitrendipine binding characteristics in diabetic heart membranes may not be due to the high levels of circulating catecholamines in this experimental model because no such changes were seen upon injecting a high dose (40 mg/kg) of isoproterenol in rats for 24 hr. The reduced number of 3H-nitrendipine binding sites may decrease Ca(2+)-influx through voltage sensitive Ca2+ channels and partly explain the depressed cardiac contractile force development in chronic diabetes whereas the increased affinity of Ca2+ channels may partly explain the increased sensitivity of diabetic heart to Ca2+.