Co-localization of histamine and norepinephrine in sympathetic ganglia and exocytosis of endogenous histamine from cardiac sympathetic nerve endings of macaca mulatto monkey

AIM To provide the evidence about localization, biosynthesis, metabolism and release of histamine from the cardiac sympathetic nerve terminals, and endogenous sympathetic histamine could inhibit itsel frelease from the nerve terminal through the presynaptic histamine H3 receptor. METHODS Using double-labeled immunohistochemistry to observe the co-localization of histamine and NE in the superior cer-vical ganglia (SCG) of macaca mulatto monkey; Different-speed centrifugation to obtain the cardiac sympathetic nerve terminal model (the cardiac synaptosomes), spectrofluorometer and ELISA techniques to detect the release of histamine from the cardiacsynaptosomes. RESULTS ( 1 ) The coexistence of histamine and norepinephrine immunoreactivities was identified in the same neuron within SCG of macaca mulatto monkey. (2) Depolarization of macaca mulatto monkey cardiac synaptosomes with 50 mmol/L potassium caused the release of endogenous histamine,