PARTICIPATION OF TRPM4/TRPM7 CHANNELS IN THE CARDIAC ACTIVITIES OF CARVACROL ON ANIMALS WITH ESSENTIAL HYPERTENSION

Abstract

IntroducionCarvacrol (CAR), a phenolic monoterpene, has been described to cause hypotension and bradychardia and in our study demonstrated a direct cardiac action of CAR in the contractility and force of isolated atria from spontaneously hypertensive (SHR) and normotensive controls rats (Wistar Kyoto ‐WKY). Then, the aim of this study it was to investigate the involvement of TRPM4 and TRPM7 channels in cardiac activities of CAR.MethodsMale SHR and WKY (250–300 g) were euthanized in CO2 chamber, and the left (LA) and right atria (RA) removed and isolated were maintained in a organ bath with krebs‐bicarbonate at a temperature of 37 ° C and aerated with a mixture carbogenic. The LA preparations were stimulated electrically continuously. The RA preparations were mounted in the same organ bath, but not were stimulated, allowing measures and rhythmicity of spontaneous contractions. The role of TRPM4 and TRPM7 in cardiac activities of CAR was investigated using channels blockers and molecular modeling tools (morphological similarity). All experimental protocols were approved by CEUA‐Animal use and care ethics committee‐ICS/UFBA (019/2011). Were considered significant values of p <0.05.ResultsIn studies with the isolated LA and RA, CAR 100μM induced significant negative chronotropic (CE) and inotropic effect (IE), respectively, in both WKY and SHR rats. To investigate the role of TRPM channels in these responses observed, TRPM4 [lanthanum 100μM (LAN), flufenamic acid 10μM (FF) and 9‐phenanthrol 10μM (9‐PHE)] and TRPM7 [magnesium 1.5mM (MG)] blockers were used. LAN, FF, 9‐PHE and MG significantly attenuated the negative CE of CAR 100μM in SHR, but not in WKY rats. However, MG significantly reduced heart automaticity in SHR and WKY rats in comparison to the control group. Interestingly, CAR in the presence of LAN, FF, 9‐PHE and MG significantly induced an additional negative IE in the SHR. Furthermore, these compounds, in the absence of CAR, reduced the cardiac contractile force in SHR in comparison to the control group. In WKY LA, the effect of CAR was changed only by 9‐PHE, but the heart contraction force was significantly reduced in the presence FF and 9‐PHE in the absence of the monoterpene. Additionally, CAR shows 86.62% chemical similarity to 9‐PHE, according to SURFLEX‐SIM software, and 9‐PHE and FF compounds have similar shape and electrostatic potential, as calculated in SYBYL®2.0, furthermore, there are data reporting that CAR inhibits TRPM7 channels in HEK cells (PARNAS et al.; 2009) and inhibits completely TRPM7 current input and output in human atrial myocytes (MACIANSKIENE et al, 2012).ConclusionsTaken together, these results suggest TRPM7 channel seems to influence heart rate and force of contraction, whereas TRPM4 channels influence in the force of contraction, at least at the atrial level. Further, CAR, along with magnesium, may act in a signaling pathway modified by hypertension. The in silico results are in good agreement with in vitro data and point out that CAR has all the chemical requirements to bind to TRPM4.Support or Funding InformationFundação de Amparo à Pesquisa do Estado da Bahia (FAPESB)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)