Presynaptic alpha 2-adrenoceptor-mediated modulation of norepinephrine release from vascular adrenergic neurons in reduced renal mass salt hypertensive rats.
The present study was designed to investigate the presynaptic alpha 2-adrenoceptor function to inhibit norepinephrine (NE) release in blood vessels of reduced renal mass salt hypertensive rats (Na-loaded HT). Isolated perfused mesenteric vasculatures were prepared from Na-loaded HT and normotensive control rats (NT-control), and the NE release and vascular responsiveness were examined. Periarterial nerve stimulation caused a significantly greater release of NE and pressor responses in Na-loaded HT than in NT-control. Yohimbine, a potent alpha 2-adrenoceptor antagonist, demonstrated the facilitatory effects on NE release during nerve stimulation. The effects were significantly attenuated in Na-loaded HT compared with NT-control. These results demonstrate that vascular sympathetic nervous activity might be enhanced in Na-loaded HT. Furthermore, the increased NE release from vascular adrenergic neurons in Na-loaded HT could partially depend on impaired presynaptic alpha 2-adrenoceptor-mediated modulation, which might contribute to the pathogenesis and maintenance of this form of salt-dependent hypertension.
Tsuda
K
K
Department of Medicine, Wakayama Medical College, Japan.
Kimura
K
K
Shima
H
H
Nishio
I
I
Masuyama
Y
Y
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004837:Epinephrine / Q000502:physiology*; D006977:Hypertension, Renal / Q000139:chemically induced / Q000378:metabolism*; D008638:Mesenteric Arteries / Q000187:drug effects / Q000294:innervation / Q000378:metabolism; D009411:Nerve Endings / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D012965:Sodium Chloride; D013564:Sympathetic Nervous System / Q000378:metabolism; D013569:Synapses / Q000502:physiology*; D015016:Yohimbine / Q000494:pharmacology
D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D012965:Sodium Chloride; D009638:Norepinephrine; D004837:Epinephrine