【摘要】 家兔40只,乌拉坦静脉麻醉,三碘季铵酚制动,人工通气,切断双侧颈迷走神经干,引导左侧膈神经干和右侧膈神经单纤维的传出电活动。在保持动物正常PaCO₂和PaO₂的条件下,所观察的144个膈神经单位,按其电活动与呼吸周期的关系,可分为三类:第一类（U_Ⅰ,占44％）,仅在吸气相放电;第二类（U_Ⅱ,41％）,放电自吸气相持续到呼气相前期;第三类（U_Ⅲ,15％）,在整个呼吸周期中连续放电。逐步加大给动物的人工通气量,在PaCO₂逐渐降低的过程中,96％的U_Ⅰ和58％的U_Ⅱ的放电频率逐渐降低,但始终保持时相性放电的特性,直至放电停止,对具有这些特性的单位称为时相性单位。其余4％的U_Ⅰ和42％的U_Ⅱ,在低PaCO₂下逐渐转为紧张性放电,将这些单位和全部U_Ⅲ称为紧张性单位。我们以前报道的家兔膈神经干的呼气相电活动,是紧张性单位活动的表现。在放电特性方面,本文报告的家兔膈神经元群中的时相性单位和紧张性单位,与Hilaire和St.John报告的猫膈神经元群中的晚募集单位和早募集单位,有类似之处,但不尽相同。更多还原

【Abstract】 Discharges of 144 phrenic motor fibers were recorded from 40 rabbits anaes-thetized with urethane, vagotomized, paralysed with flaxedil and artificially venti-lated. Under normal PaCO₂ and PaO₂, the phrenic motoneurons were divided intothree types according to their different discharge duration in a respiratory cycle:type Ⅰ（44%）, discharging only in the inspiratory phase; type Ⅱ（41%）, firing inthe inspiratory phase and early portion of the expiratory phase; type Ⅲ（15%）,showing tonic discharges throughout the respiratory cycle. As PaCO₂ reduced, 96% of type Ⅰ units and 58% of type Ⅱ units retained thephasic discharge feature but decreased in discharge frequency; discharges of theother 4% of type Ⅰ and 42% of type Ⅱ gradually became tonic. The former werephasic units, and the latter together with type Ⅲ were tonic units. Some electrophysiological characteristics of the tonic units and phasic unitslesembled respectively the early units and late units of cat phrenic motoneurons. Evidence was provided that discharges during expiratory phase of the rabbitphrenic nerve previously reported by this laboratory, reflected the activities of thetonic units.更多还原