ARTERIAL BARORECEPTOR REFLEX IN GROWING RATS
10.7600/jspfsm1949.34.131
- Author:
MAMORU SAITO
;
NAOHITO TERUI
;
YOSHINOBU NUMAO
;
MAMORU KUMADA
- Publication Type:Journal Article
- Keywords:
growing rats;
neural control of circulation;
arterial baroreceptor reflex;
bradycardia;
cardiac vagus
- From:Japanese Journal of Physical Fitness and Sports Medicine
1985;34(Supplement):131-140
- CountryJapan
- Language:English
-
Abstract:
In order to characterize the neural control of the circulation in an organism undergoing a rapid somatic growth, we compared the arterial baroreceptor reflex in two groups of male Wistar rats anesthetized with urethane. The first group consisted of 36 rats of 6-7 weeks old, known to exhibit the greatest rate of increase of the body weight during the life span, whereas the second group consisted of 30 full-grown rats of 20-22 weeks old. When arterial pressure was controlled by phenylephrine or nitroglycerin, the reflex change in renal nerve activity was elicited over the arterial pressure range 15-30 mmHg lower than that of full-grown rats. The difference was attributable partly, but not exclusively, to the lower operating range of arterial baroreceptors in the former groups. Although no difference was observed between the two groups with respect to the reflex fall in arterial pressure in response to graded electrical stimulation of the aortic nerve, the accompanying bradycardia was significantly smaller in 6-7 weeks old rats primarily due to the difference in the vagally mediated component of the reflex response. In conclusion, the arterial baroreceptor reflex of growing rats, as compared to full-grown counterparts, is characterized by deviation of the operating range of arterial baroreceptors as well as the arterial baroreceptor reflex itself to lower arterial pressure range and poor development of the vagally mediated reflex bradycardia.
