Guinea pig right atria

In a more recent work, additional esters (89) derived from aromatic and heterocyclic alcohols were investigated to improve the lipophilic character and enhance the in vivo potency, biodistribution, and duration profile (198). A number of these esters showed consistent ability to convert acetylstrophanthidin-induced arrhythmias in guinea pig right atria to normal sinus rhythm with an EDgo value of less than 10 /xg/mL. Based on their shorter half-life in human blood, esters (90)(ty2 = 3.5 min) and (91)( i/2 = 7.1 min) were selected for in vivo evaluation. They both demonstrated greater potency than that of lidocaine in the 24-h Harris dog model and equal potency to lidocaine in the oubaine-intoxicated dog model (198). In addition, the lipophilicity of these compounds was lower than that of lidocaine, suggesting a lower ability to penetrate the blood—brain barrier and, thus, lower CNS liability. Considering all these observations, (91) was chosen as a potential development... 

Guinea Pig Right Atria Test (30). Isolated guinea pig right atria were suspended in an aerated (95% O2 - 5% CO2) bath of Krebs... 

The application of high concentrations (above 5 x 10 g/mL) of MTX caused a biphasic inotropic change and gradual rise in diastolic tension of the atria. Furthermore, MTX produced various arrhythmic movements and cardiac arrest in the guinea pig left and right atria (Figure 4). 

Figure 4. Effect of maitotoxin (MTX, 2-6 x 10 g/mL) on the contractile response of guinea pig left (a) and right (b) atria. MTX was administered at the arrow. Numbers above the tracing indicate the times after the application of MTX. The horizontal calibration indicates 4 min for the tracing recorded at a slower sweep speed and 4 sec for that recorded at faster speed. (Reproduced with permission from Ref. 20. Copyright 1987 Elsevier)...

Dimech, J. et al. (1993) Antagonist effects of seglitide (MK 678) at somatostatin receptors in guinea-pig isolated right atria. Br. J. Pharmacol.. 109.898-899. Wilkinson. G.F. et al. (1996) Potent antagonism by BlM-23056 at the human recombinant somatostatin ssts receptor. Br.J. Pharmacol.. 118, 445-447. Alexander. S.P.H. et al. (1998) Receptors and ion channel nomenclature supplement. Ninth Edition. Trends Pharmacol. Set.. Suppl., 19,1-98. 

The compound sanguinarine had a positive inotropic effect followed by contracture in rat ventricular and atrial strips. Sanguinarine also dose-dependently reduced the rate of spontaneous contractions of isolated right atria (Hu et al. 2005). Positive inotropic effects were also observed in isolated guinea pig atria treated with the compound sanguinarine (Seifen et al. 1979). A dose-dependent response in ventricular refractoriness was observed in anesthetized pigs after vascular infusion of up to 4 mg/kg of the compound sanguinarine (Whittle et al. 1980). 

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