Rutlen D L
Am J Physiol. 1981 Nov;241(5):H760-5. doi: 10.1152/ajpheart.1981.241.5.H760.
The reflex autonomic influence of left atrial baroreceptor stimulation on the total capacitance vasculature has not been examined. To this end, left atrial pressure was increased in 25 anesthetized dogs, in which blood from the vena cavae was drained into an extracorporeal reservoir and returned to the right atrium at a constant rate, so that changes in intravascular volume could be recorded as reciprocal changes in reservoir volume. Left atrial pressure was elevated from 5 +/- 1 (mean +/- SE) to 11 +/- 1 mmHg by inflating a balloon at the mitral orifice for 12-20 min. With left atrial pressure elevation, total intravascular volume decreased 25 +/- 10 ml (P less than 0.025). In six of the dogs, intravascular volume decreased 37 +/- 12 ml with left atrial pressure elevation before bilateral cervical vagectomies and increased 66 +/- 8 ml with atrial pressure elevation after vagectomies (P less than 0.001). In eight of the dogs, volume decreased 42 +/- 19 ml with atrial pressure elevation before propranolol administration and increased 44 +/- 29 ml after propranolol (P less than 0.03). Phenoxybenzamine in five of the animals and atropine in three did not attenuate the change in intravascular volume with left atrial pressure elevation. Thus left atrial baroreceptor stimulation is associated with an autonomic reflex, which acts to decrease intravascular volume. The afferent limb is mediated by the vagi, and the efferent limb, by beta-adrenergic receptor stimulation.
左心房压力感受器刺激对总容量血管的反射性自主神经影响尚未得到研究。为此，对25只麻醉犬升高左心房压力，将腔静脉血引流至体外储液器，并以恒定速率回输至右心房，以便将血管内容量的变化记录为储液器容量的反向变化。通过在二尖瓣口充盈气囊12 - 20分钟，将左心房压力从5±1（均值±标准误）mmHg升高至11±1 mmHg。随着左心房压力升高，血管内总容量减少25±10 ml（P<0.025）。在6只犬中，双侧颈迷走神经切断术前左心房压力升高时血管内容量减少37±12 ml，迷走神经切断术后心房压力升高时血管内容量增加66±8 ml（P<0.001）。在8只犬中，给予普萘洛尔前心房压力升高时容量减少42±19 ml，给予普萘洛尔后增加44±29 ml（P<0.03）。5只动物使用酚苄明和3只动物使用阿托品并未减弱左心房压力升高时血管内容量的变化。因此，左心房压力感受器刺激与一种自主神经反射相关，该反射作用是减少血管内容量。传入支由迷走神经介导，传出支由β - 肾上腺素能受体刺激介导。
