Abstract
The pH optimum for rat serum dopamine beta-hydroxylase (DBH) (3,4-dihydroxyphenylethylamine, ascorbate:oxygen oxidoreductase (beta-hydroxylating)(EC 1.14.17.1) was 4.0 in acetate buffer; other requirements were as reported by others. DBH activity in serum of 20-day-old fetuses is slightly higher than in that of their mothers. Levels of the enzyme in blood a few hours after birth are almost five times greater than in the adult, remain high during the suckling period, then drop rapidly during the 4th week after birth to about three times the adult level, which is then slowly reached over the next few weeks. These fluctuations in serum DBH activity coincide with the period of intense development and maturation of the sympathetic nervous system. There was not significant effect of cold exposure on blood DBH activity when newborn, suckling, weanling or adult warm- and cold-acclimated rats were exposed to cold. Similarly, exposure to cold that elicited two- to three-fold increases in O2 consumption failed to increase DBH activity in thoracic duct lymph. Therefore serum and lymph DBH activities are not sensitive indices of sympathetic secretory activity in the intact rat.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
