- 著者
-
Tsuji Tsuyoshi
Ohga Yoshimi
Yoshikawa Yoshiro
SAKATA Susumu
KOHZUKI Hisaharu
MISAWA Hiromi
ABE Takehisa
TABAYASHI Nobuoki
KOBAYASHI Shuichi
KITAMURA Soichiro
TANIGUCHI Shigeki
SUGA Hiroyuki
TAKAKI Miyako
- 出版者
- 一般社団法人 日本生理学会
- 雑誌
- The Japanese journal of physiology (ISSN:0021521X)
- 巻号頁・発行日
- vol.49, no.6, pp.513-520, 1999-12-01
- 参考文献数
- 20
- 被引用文献数
-
7
23
We have already reported the linear oxygen consumption per beat (Vo<sub>2</sub>)–systolic pressure-volume area (PVA) relation from the curved left ventricular (LV) end-systolic pressure–volume relation (ESPVR) in the cross-circulated rat heart. The Vo<sub>2</sub> intercept (PVA-independent Vo<sub>2</sub>) is primarily composed of Vo<sub>2</sub> for Ca<sup>2+</sup> handling in excitation-contraction (E-C) coupling and basal metabolism. The aim of the present study was to obtain the oxygen cost of LV contractility that indicates Vo<sub>2</sub> for Ca<sup>2+</sup> handling in E-C coupling per unit LV contractility change in the rat heart. Oxygen cost of LV contractility is obtainable as a slope of a linear relation between PVA-independent Vo<sub>2</sub> and LV contractility. We obtained a composite Vo<sub>2</sub>–PVA relation line at a mid-range LV volume (mLVV) under gradually enhanced LV contractility by stepwise increased Ca<sup>2+</sup> infusion and thus the gradually increased PVA-independent Vo<sub>2</sub> values. As a LV contractility index, we could not use E<sub>max</sub> (ESP-V ratio; ESP/ESV) for the linear ESPVR because of the curved ESPVR in the rat LV. A PVA at a mLVV (PVA<sub>mLVV</sub>) has been proposed as a good index for assessing rat LV mechanoenergetics. Since the experimentally obtained PVA<sub>mLVV</sub> was not triangular due to the curved ESPVR, we propose an equivalent ESP-V ratio at a mLVV, (eESP/ESV)<sub>mLVV</sub>, as a LV contractility index. This index was calculated as an ESP-V ratio of the specific virtual triangular PVA<sub>mLVV</sub> that is energetically equivalent to the real PVA<sub>mLVV</sub>. The present approach enabled us to obtain a linear relation between PVA-independent Vo<sub>2</sub> and (eESP/ESV)<sub>mLVV</sub> and the oxygen cost of LV contractility as the slope of this relation.<br>