title: Interrelationship between plasma ionized calcium, plasma noradrenaline (NA) and pressor response to infused NA in patients with essential hypertension.
abstract: We evaluated the role of calcium metabolism on plasma noradrenaline concentration (pNA) and pressor response to infused noradrenaline (NA-R) in patients with mild-to-moderate essential hypertension (EHT). Mean arterial pressure (MAP), plasma ionized calcium (pCa2+), and NA-R were measured at the basal condition in 17 EHT and after the administration of calcium antagonist, nifedipine (60mg, t.i.d., for 4 weeks) in 9 EHT. Under basal condition, pCa2+ correlated positively with pNA and negatively with NA-R in EHT. Following nifedipine therapy, persistent reductions of MAP and NA-R, a transient increase in pNA and a sustained increase of urinary excretion of calcium were observed. On the other hand, no significant change in pCa2+ was found during the therapy. Percent change in MAP following 4 weeks of nifedipine administration correlated positively with pCa2+ and pNA before the therapy. In addition, change in NA-R by nifedipine therapy correlated positively with the basal values of pCa2+ and PNA and negatively with NA-R before the treatment. A significant negative correlation between NA-R and pNA was observed following nifedipine therapy as well as the basal state. However, the slope of the regression line between NA-R and pNA decreased significantly after the treatment as compared to the basal state. These results suggest that calcium metabolism relating sympathetic nerve activity and NA-R may contribute to the hypertensive mechanism in EHT. The hypotensive effects of nifedipine may be caused partly by the attenuation of sympathetic nerve activity and NA-R.
authors.affiliation: 2nd Department of Internal Medicine, Sapporo Medical College, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Nozawa
authors.forename: K
authors.initials: K
authors.lastname: Kikuchi
authors.forename: M
authors.initials: M
authors.lastname: Nishimura
authors.forename: T
authors.initials: T
authors.lastname: Hasegawa
authors.forename: C
authors.initials: C
authors.lastname: Honma
authors.forename: H
authors.initials: H
authors.lastname: Komura
authors.forename: H
authors.initials: H
authors.lastname: Kobayakawa
authors.forename: S
authors.initials: S
authors.lastname: Suzuki
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: S
authors.initials: S
authors.lastname: Shimazaki
mesh_terms: D001794:Blood Pressure / Q000187:drug effects*; D002118:Calcium / Q000097:blood*; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000503:physiopathology*; D007262:Infusions, Intravenous; D007477:Ions; D009543:Nifedipine / Q000494:pharmacology; D009638:Norepinephrine / Q000097:blood* / Q000494:pharmacology; D009994:Osmolar Concentration
chemical_list: D007477:Ions; D009543:Nifedipine; D002118:Calcium; D009638:Norepinephrine