Optimising conditions for studying the acute effects of drugs on indices of cardiac contractility and on haemodynamics in anaesthetized guinea pigs

Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK.
Journal of pharmacological and toxicological methods (Impact Factor: 2.39). 05/2012; 66(1):43-51. DOI: 10.1016/j.vascn.2012.05.008
Source: PubMed


Detecting adverse effects of drugs on cardiac contractility is becoming a priority in pre-clinical safety pharmacology. The aim of this work was to optimise conditions and explore the potential of using the anaesthetized guinea pig as an in vivo model.
Guinea pigs were anaesthetized with Hypnorm/Hypnovel, isoflurane, pentobarbital or fentanyl/pentobarbital. The electrocardiogram (ECG), heart rate, arterial blood pressure and indices of cardiac contractility were recorded. In further experiments in fentanyl/pentobarbital anaesthetized guinea pigs the influence of bilateral versus unilateral carotid artery occlusion on haemodynamic responses was investigated and the effects of inotropic drugs on left ventricular (LV) dP/dt(max) and the QA interval were determined.
Pentobarbital, given alone or after fentanyl, provided suitable anaesthesia for these experiments. Bilateral carotid artery occlusion did not alter heart rate or arterial blood pressure responses to isoprenaline or angiotensin II. Isoprenaline and ouabain increased LVdP/dt(max) and decreased the QA interval whereas verapamil had opposite effects and strong inverse correlations between LVdP/dt(max) and the QA interval were found.
Conditions can be optimised to allow the pentobarbital-anaesthetized guinea pig to be used for simultaneous measurement of the effects of drugs on the ECG, haemodynamics and indices of cardiac contractility. The use of this small animal model in early pre-clinical safety pharmacology should contribute to improvements in detecting unwanted actions on the heart during the drug development process.

13 Reads
    • "After administration of the vasodilating drug SNP reflex tachycardia was observed. Although reflex bradycardia after infusion of L-phenylephrine has recently been shown in pentobarbital anesthetized guinea-pigs (Mooney et al., 2012), in our hands neither bolus (data not shown) nor slow (10 min) infusions of L-phenylephrine caused reflex bradycardia even though decreases in arterial blood pressure were observed. This absence of reflex bradycardia could be ascribed to the inhibitory effect of pentobarbital on Fig. 2. Graphs show actual changes from baseline of multiple reference compounds on the heart rate (panel a), the mean arterial blood pressure (panel b), the rate of the LVP contraction (LV dP/dt max ; panel c) and the QA interval (panel d). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Evaluation of drug-related effects on cardiovascular function is part of the core battery described in the ICH S7A guideline. Anesthetized guinea-pigs are excellent models for the evaluation of drug-induced prolongation of ventricular repolarization; however less information is available regarding other cardio-hemodynamic parameters in this model. The current study aimed to document cardio-hemodynamic responses in anesthetized guinea-pigs after administration of a number of reference drugs with known pharmacological actions.
    Journal of pharmacological and toxicological methods 07/2012; 66(2):152-9. DOI:10.1016/j.vascn.2012.07.002 · 2.39 Impact Factor
  • Source

    Journal of Pharmacological and Toxicological Methods 07/2011; 64(1). DOI:10.1016/j.vascn.2011.03.011 · 2.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Despite rigorous preclinical and clinical safety evaluation, adverse cardiac effects remain a leading cause of drug attrition and post-approval drug withdrawal. A number of cardiovascular screens exist within preclinical development. These screens do not, however, provide a thorough cardiac liability profile and, in many cases, are not preventing the progression of high risk compounds. We evaluated the suitability of the anaesthetised guinea-pig for the assessment of drug-induced changes in cardiovascular parameters. Sodium pentobarbitone anaesthetised male guinea-pigs received three 15 minute intravenous infusions of ascending doses of amoxicillin, atenolol, clonidine, dobutamine, dofetilide, flecainide, isoprenaline, levosimendan, milrinone, moxifloxacin, nifedipine, paracetamol, verapamil or vehicle, followed by a 30 minute washout. Dose levels were targeted to cover clinical exposure and above, with plasma samples obtained to evaluate effect/exposure relationships. Arterial blood pressure, heart rate, contractility function (left ventricular dP/dt(max) and QA interval) and lead II electrocardiogram were recorded throughout. In general, the expected reference compound induced effects on haemodynamic, contractility and electrocardiographic parameters were detected confirming that all three endpoints can be measured accurately and simultaneously in one small animal. Plasma exposures obtained were within, or close to the expected clinical range of therapeutic plasma levels. Concentration-effect curves were produced which allowed a more complete understanding of the margins for effects at different plasma exposures. This single in vivo screen provides a significant amount of information pertaining to the cardiovascular risk of drug candidates, ultimately strengthening strategies addressing cardiovascular-mediated compound attrition and drug withdrawal.
    Toxicology and Applied Pharmacology 06/2012; 263(2):171-83. DOI:10.1016/j.taap.2012.06.007 · 3.71 Impact Factor
Show more