血中心房性ナトリウム利尿ホルモン分泌に及ぼす慢性容量負荷の影響

Effects of chronic volume loading on atrial natriuretic peptide release in human

　ヒトにおける慢性容量負荷でのANP分泌動態を明らかにするために，2日間にわたる容量負荷時の血中hANP濃度（ANP）と循環動態パラメーター等との関連を検討した。

　化学療法の前に，多量の水分負荷を必要とする全身状態良好な癌患者8症例を対象とし，Swan-Ganz　catheterを留置し，維持輸液製剤を平均0.042 ml／分／kgで点滴した。

　水分負荷により，血漿量変化率（APV）は5.8±3.3（mean±SE）％，肺動脈襖入圧（PAWP）は4.3±1.0から5.8±0.7mmHgへ有意に上昇し，血中アルドステロンは，有意に低下したが，抗利尿ホルモン（ADH）は変化なかった。ANPは50.6±11.4から105.1±19.3pg／mlへ有意に上昇し，1日目と2日目の同時刻の比較ではΔPV，PAWP，右心房圧（RAP）に変化がみられないにもかかわらず，ANPは有意な上昇が認められた。

　容量負荷で，ANP分泌は心房圧の上昇の程度と相関するといわれているが，慢性容量負荷では，その他に心房圧上昇の持続が重要であることが示唆された。

In the present study, we investigated whether release of hANP increases during mild and long-term volume loading.

Eight lung cancer patients in good performance state (five men and three women, 35 to 68 years), who needed to have prehydration for cancer che-motherapy with cisplatin, were infused with about seven liters of isotonic saline over 48 hours through Swan-Ganz catheter placed in the pulmonary artery. The mean infusion rate was 0.042 m/min･kg body weight.

During the infusion, change in plasma volume (ΔPV) increased by 5.8+3.3(mean±SE)%. Right atrial pressure (RAP) did not change significantly, and pulmonary artery wedge pressure (PAWP) in-creased from 4.3±1.0 to 5.8±0.7mmHg. Plasma hANP was significantly elevated from 50.6±0.7 to 105.1±19.3pg/ml by the second day of the infusion with a suppression of plasma renin activity (PRA) and aldosterone, though plasma ADH did not change. The infusion rate at 20:00 on the first day was the same as that on the second day. Further increase in plasma hANP was shown at 20:00 on the second day compared with the level at the same time on the first day, though RAP, PAWP and JPV did not change.

These results indicate that mild and chronic vol-ume loading increases plasma hANP, and suggest that the prolongation of volume expansion plays an important role in the releasing of hANP in humans.