Document Detail

Cardiovascular and eletrocardiographic parameters after tonin administration in Wistar rats.
MedLine Citation:
PMID:  23318501     Owner:  NLM     Status:  Publisher    
In order to understand the mechanisms of interaction between tonin-angiotensin and renin-angiotensin systems (RAS) we evaluated, "in vivo" and "in vitro", in Wistar rats, cardiovascular and electrocardiographic parameters after tonin administration. Arterial pressure (AP) and electrocardiogram (ECG) were recorded in awake animals before and after tonin administration. Langendorff technique was used to analyze cardiac function in isolated heart on the presence of tonin and video motion edge detection system was used to evaluate the effect of tonin upon contractile function of isolated rat ventricular cardiomyocytes. After tonin infusion rats presented significantly higher diastolic and mean arterial pressure (MAP) and heart rate (HR) as compared with control. The ECG analysis revealed shorter RR interval, increase in the low-frequency (LF) range of the heart rate variability (HRV) power (%) and decrease in the high-frequency (HF) of HRV power (%). Isolated hearts perfused with tonin presented an increase in the arterial coronary pressure (ACP) and decline in the ventricular systolic tension (ST), maximal (dT/dt+) and minimal (dT/dt) contractility. The rates of contraction and relaxation of isolated ventricular cardiomyocytes were significantly increased due to the presence of tonin. The angiotensin II (Ang II) levels in the coronary sinus effluent increased in the presence of tonin in a dose-dependent manner and the effect of tonin upon ACP was completely blocked by candesartan. Tonin is able to generate the vasoconstrictor peptide Ang II in the isolated heart of the rat and the cardiovascular response induced by tonin was completely blocked by candesartan, an indication that the action of Ang II on Ang II type 1 (AT1) receptors is the major mechanism of the heart effects. Tonin affects cardiomyocyte contractile function which may be due to interference with Ca(2+) handling.
Denis D Damasceno; Mercia P Lima; Daisy F Motta; Anderson J Ferreira; Judson F Quintão-Junior; Lucas R Drummond; Antônio J Natali; Alvair P Almeida; Jorge L Pesquero
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-11
Journal Detail:
Title:  Regulatory peptides     Volume:  -     ISSN:  1873-1686     ISO Abbreviation:  Regul. Pept.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-15     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8100479     Medline TA:  Regul Pept     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier B.V.
Department of Educational Development, Federal Institute of Education, Science and Technology of Southeast Minas Gerais, Campus Barbacena, MG, Brazil; Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil. Electronic address:
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