Relationship between QaT and RR intervals in rats, guinea pigs, rabbits, and primates.

The ECG is routinely used in many species to monitor effects of drugs. While it is relatively easy to measure both PR and QRS, measurement of QT is complicated by the fact that this interval can change with heart rate. In order to compensate for variations in QT due to variations in heart rate, various correction factors have been used, including those of Bazett and Hodges.

Cardiovascular actions of the kappa-agonist, U-50,488H, in the absence and presence of opioid receptor blockade.

1. The cardiovascular actions of U-50,488H, a kappa-receptor agonist, were studied in rat isolated perfused hearts, and in anaesthetized rats, over concentrations or doses generally above those required to produce kappa-receptor-mediated effects. 2.

A new ECG measure (RSh) for detecting possible sodium channel blockade in vivo in rats.

A new electrocardiographic (ECG) measure for detecting possible sodium channel blocking actions of drugs in anaesthetized rats is described. The conventional measures for sodium channel blockers are increased QRS width and/or P-R prolongation, however, these are limited in their sensitivity. This new measure, RSh, is the height from the peak of the R wave to the bottom of the S wave; it is more sensitive to known sodium channel blocking agents than conventional measures.

Antiarrhythmic effects of U-50,488H in rats subject to coronary artery occlusion.

The antiarrhythmic actions of low and high doses of U-50,488H, a selective kappa-receptor agonist, were examined in pentobarbitone-anaesthetized rats subjected to occlusion of the left anterior descending coronary artery. At a high dose (16 mumol/kg) U-50,488H reduced blood pressure, heart rate and prolonged the P-R and QRS intervals of the electrocardiogram. This dose reduced the incidence of ventricular arrhythmias produced by occlusion.