Dynamic properties of a retrograde superfusion system for isolated right atria including effects of histamine H2 receptor agonists.

A retrograde superfusion technique is described for spontaneously beating guinea pig right atrium where both force of contraction and rate are recorded simultaneously. Drugs are applied to the system in bolus injections and the concentrations attained in the organ bath after these injections are computed through an analog system by means of measuring injected dye dilutions in a spectrophotometer. Actions of histamine and histamine H2-receptor agonists 4-methyl histamine, dimaprit, and impromidine on the preparation for the mentioned parameters are investigated. By comparing responses to bolus injections with infusions of agonists, it is concluded that all four agonists tested are rapidly passing to the biophase, and the system can be used as an alternative for the classical organ bath. Dose-response characteristics of the tested agonists are satisfactory and affinity values found are in agreement with the values reported for bathed systems.