Jiao J H, Baertschi A J
Department of Molecular Physiology and Biological Physics, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
Am J Physiol. 1995 Apr;268(4 Pt 2):H1405-11. doi: 10.1152/ajpheart.1995.268.4.H1405.
The interaction between cardiac sympathetic stimulation of atrial natriuretic factors (ANF) release and left atrial stretch was examined in groups (n = 5 or 6) of isolated, perfused (10 ml/min), paced rat hearts. Left atrial stretch, produced by an increase in atrial pressure of 1.1 +/- 0.2 mmHg over 8 min, transiently (4 min) increased ANF release by 46 +/- 4% over baseline (220 pg/ml buffer; P < 0.05). Infusion of 1 microM norepinephrine (NE) over 28 min caused a sustained increase in ANF release of 76 +/- 10% (P < 0.05). Atrial stretch plus NE caused additive effects on ANF release during stretch but 2.4 times the additive effects after stretch (P < 0.05). To examine whether resting tension modulates the ANF response to sympathetic stimulation, the left atrium was stretched throughout the experiment by increasing the atrial pressure by 1-1.5 mmHg. Infusion of 1 microM NE over 28 min increased ANF release by 216 +/- 46% (P < 0.01) in the prestretched heart, compared with a calculated summed increase of 85% due to NE alone plus prestretch alone. Infusion of 0.5 microM veratridine, known to stimulate ANF via mechanical effects on the heart, increased ANF release by 88 +/- 3% (P < 0.01). Scorpion venom, known to dose dependently stimulate ANF secretion via activation of neuronal sodium channels, elicits a negligible increase in ANF release at the threshold concentration of 0.1 microM. The combined infusion of 0.5 microM veratridine plus 0.1 microM venom increased ANF release by 239 +/- 53% (n = 6, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
在多组（每组n = 5或6）离体、灌注（10毫升/分钟）、起搏的大鼠心脏中，研究了心脏交感神经刺激心房利钠因子（ANF）释放与左心房牵张之间的相互作用。通过在8分钟内将心房压力升高1.1±0.2毫米汞柱产生左心房牵张，可使ANF释放量在4分钟内短暂（相对于基线）增加46±4%（基线为220皮克/毫升缓冲液；P<0.05）。在28分钟内输注1微摩尔去甲肾上腺素（NE）可使ANF释放持续增加76±10%（P<0.05）。心房牵张加NE在牵张期间对ANF释放有相加作用，但在牵张后是相加作用的2.4倍（P<0.05）。为了研究静息张力是否调节ANF对交感神经刺激的反应，在整个实验过程中通过将心房压力升高1 - 1.5毫米汞柱来牵张左心房。在预牵张的心脏中，在28分钟内输注1微摩尔NE使ANF释放增加216±46%（P<0.01），相比之下，仅NE加上仅预牵张的计算相加增加量为85%。输注0.5微摩尔藜芦碱（已知通过对心脏的机械作用刺激ANF）可使ANF释放增加88±3%（P<0.01）。已知蝎毒通过激活神经元钠通道剂量依赖性地刺激ANF分泌，在阈值浓度0.1微摩尔时引起的ANF释放增加可忽略不计。联合输注0.5微摩尔藜芦碱加0.1微摩尔蝎毒可使ANF释放增加239±53%（n = 6，P<0.01）。（摘要截断于250字）
