Temperature alters the inotropic, chronotropic and proarrhythmic effects of histamine in atrial muscle preparations from humans and H-receptor overexpressing mice.

We investigated whether hypothermia and hyperthermia can alter the efficacy and potency of histamine at increasing the force of cardiac contractions in mice that overexpress the human H receptor only in their cardiac myocytes (labelled H-TG). Contractile studies were performed in an organ bath on isolated, electrically driven (1 Hz) left atrial preparations and spontaneously beating right atrial preparations from H-TG mice and wild-type (WT) littermate control mice. The basal beating rate in the right atrial preparations from H-TG mice was lowered by hypothermia (23 °C) and elevated by hyperthermia (42 °C).