Morphology and function of myocardium and skin microcirculation 24 hours after clozapine poisoning (Experimental study)

Aim of the study: to evaluate the effect of sublethal dose of clozapine on the rat cardiovascular system 24 hours after administration of the drug. Materials and methods. The experiments were carried out on 17 male Wistar rats weighing 220–270 g. Under general anesthesia with sevoflurane, the animals of Group I were enterally given 0.9% NaCl solution, Group II animals received clozapine in a dose of 150 mg/kg diluted in 2.0 ml of NaCl solution 0.9%, Group III animals were given clozapine in a dose of 150 mg/kg diluted in 2.0 ml of 40% ethanol. Blood pressure (BP), heart rate (HR), skin microcirculation using laser Doppler flowmetry (LDF), NADH and FAD+ fluorescence were estimated 24 hours after the drug administration. After euthanasia, autopsy with sampling of internal organs for morphological study was done. Then paraffin heart sections with subsequent H&E staining were made, which were studied using the Nikon Eclipse Ni-U light microscope. Results. Spectral analysis of local skin blood flow fluctuations showed that clozapine reduced Amax and amplitude in all frequency ranges of active microcirculation regulatory system in comparison with the controls. No differences in blood gases and acid-base status were seen between the groups of animals 24 hours after administration of the drugs. However, the animals from clozapine groups (II and III) had lower hemoglobin and hematocrit than in the control group. Histological examination of rat hearts in groups II and III revealed congested venules, haemorrhages by diapedeses, perivascular and interstitial edema. The signs of blood stasis and marginalization of granulocytes were noted in the vascular lumen. Irregular staining of myocardium due to cardiomyocytes with hypereosinophilic and occasionally homogeneous cytoplasm, fragmentation and deformations of cardiac cells were revealed. Cardiomyocytic nuclei were polymorphic and irregularly stained, and perinuclear edema was observed. Conclusions. The results of the study demonstrate the toxic effect of clozapine manifesting as progressive myocardial alteration and disordered central and peripheral circulation. However, control of bradycardia, restored skin perfusion and metabolic improvement (diagnosed by NADH fluorescence and blood acid-base status) after 24 hours may be due to the activation of compensatory mechanisms, particularly through changes in neurogenic and humoral regulation of homeostasis. © 2020, V.A. Negovsky Research Institute of General Reanimatology. All rights reserved.