Adrenergic control in three artery segments of diminishing diameter in rabbit ear.

摘要: The adrenergic neuroeffector mechanism has been assessed in three different-sized vessels of the rabbit ear, i.e., central ear artery (CEA), which an unstretched lumen diameter (ULD) approximately 300 micron; a main side branch (MSB) that comes off CEA immediately distal to crossover position vein (ULD approx 150 micron); and terminal (TB) originates from MSB 75 micron). receive innervation limited adventitia as by fluorescence histochemistry. Density innervation, indexed neuronal uptake tritiated norepinephrine (NE) NE content expressed terms surface area vascular segment, appears greater larger vessel than small vessels. neurogenic contractile response isolated segments relation maximum iota-NE was significantly smaller vessels; this paralleled density. Phentolamine (10(-6) M) blocked neurally evoked contractions at 2 Hz depressed contraction least 90% 4 8 Hz. All arterial constricted histamine with equal maximal effects. Sensitivity appeared equal, whereas Only two possessed intrinsic tone. On basis substantial studied, (substantive) sympathetic control tone occurs fact may be related temperature regulation role bed.