Inotropic response to endothelin‐1, isoprenaline and calcium in cardiomyocytes isolated from endotoxin treated rats: effects of ethyl‐isothiourea and dexamethasone

The contractile effects of endothelin‐1, isoprenaline and extracellular calcium were assessed on ventricular cardiomyocytes isolated from lipopolysaccharide‐treated rats. The involvement of nitric oxide was investigated using dexamethasone (in vivo) and ethyl isothiourea (in vitro). Male Wistar rats (n=70) were injected with either saline (1 ml kg−1) or lipopolysaccharide (LPS; 5 mg kg−1) alone, or following pre‐treatment with dexamethasone (DEX+LPS; 5 mg kg−1). Ventricular cell shortening was recorded using a video edge detection system, and concentration‐response relationships were established for endothelin‐1, isoprenaline and calcium, in the absence or presence of ethyl isothiourea (ETU; 10 μM). iNOS expression was assessed using reverse transcription‐polymerase chain reaction. iNOS mRNA expression was greater (P