Increasing intraluminal right atrial pressure directly increases inotropic and chronotropic responses in isolated mammalian hearts up to 5-15 mm Hg, likely due to stretch-induced alterations in pacemaker membrane metabolism.
The effect of increasing the intraluminal pressure in the right heart on the activity of isolated perfused dog hearts and the effect of increasing the intraluminal pressure on the activity of isolated right atria of dogs, rabbits, guinea pigs and albino rats have been studied. It has been observed that there is a direct relationship between the magnitude of intraluminal right atrial pressure and the inotropic and chronotropic responses of the whole heart and right atrium up to certain critical pressures (5–15 mm Hg). Some modifications in this behavior of the hearts due to repeated changes in the intraluminal pressure have also been described. It has been suggested that stretch of the cardiac tissue due to increased intraluminal pressure may cause alterations in membrane metabolism at the pacemaker.
Chintamani Pathak (Tue,) studied this question.
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