[SHORT REPORTS]The Influence of Intrinsic Pacemaking Activity and Animal Body Weight on the Positive Chronotropic Response of the Sinoatrial Node to Mechanical Stretch

概要

論文の詳細を見る
In 119 sinoatrial (SA) node tissue preparations isolated from rabbit hearts, we evaluated between the positive chronotropic response to mechanical stretch against the animal's basal spontaneous beating rate (BSR) and body weight (BW). All preparations were divided into thress groups based on BSR (beats/min): low rate (103-120), intermediate rate (121-160), and high rate (161-200). There were also three goups based on BW(kg): small sized (1.3-1.49), middle sized (1.5-1.69) and large sized (1.7-1.9). In all goups, the spontaneous beating rate (SR) was increased in a force-dependent manner by a 5 sec stretsh ranging from 0.2 to 2.0g. BSR had little effect on the chronotropic rsponse: Increasing SR to the maximal force was attenuted in little in the highrate gorup. However, the chronotropic response clearly depended on BW: The increase in SR was significantly lower in the large-sized group than in the small- and middle-sized groups over the entire range of the stretch. An increase in BW from 1.3kg to 1.9kg corresponded to rabbits at 5-8 weeks after birth. Our results, therefore, suggest that the attenuation of SA node pacemaking activity induced by mechanical stimulation is associated with animal growth.
名古屋大学の論文