AJP - Heart and Circulatory Physiology, Vol 256, Issue 6 1580-H1587, Copyright © 1989 by American Physiological Society

ARTICLES

Effect of diltiazem on aortic pressure-diameter relationship in dogs

M. Yano, T. Kumada, M. Matsuzaki, M. Kohno, T. Hiro, S. Kohtoku, T. Miura, K. Katayama, M. Ozaki and R. Kusukawa
Second Department of Internal Medicine, Yamaguchi University School of Medicine, Japan.

To study the effects of diltiazem (Dz) on aortic (Ao) pressure-diameter (P-D) relationships, the external diameter (D) of the thoracic Ao (sonomicrometry) and Ao pressure (AoP, micromanometer) were simultaneously measured in 10 anesthetized dogs. The P-D relationship from 80 ms after the dicrotic notch of AoP (t80) to 20 ms after the peak of the next R wave on the electrocardiogram (ECG) (t20) was plotted at 30-ms intervals. To depict the P-D relationship in a wide range of AoP, Ao occlusion immediately after the release of inferior vena caval (IVC) occlusion was performed both before and after a Dz (0.03 mg.kg-1.min-1, over 10 min) infusion. The P-D relationship so obtained was a sigmoid curve under both conditions and was reasonably described by a cubic curve (P = aD3 + bD2 + cD + d, where a, b, c, and d are constants and r greater than 0.99). The first derivative of cubic regression equation (dP/dD) value of the cubic curve was used as an index of Ao stiffness. In all dogs, the dP/dD-D relationship, which was parabolic, was similar to the delta P/delta D-D relationship measured from the actual P-D relationship (delta P/delta D is the ratio of the change in AoP to that in AoD), suggesting that it corresponded to a cubic curve.(ABSTRACT TRUNCATED AT 250 WORDS)

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