title: Effect of naloxone on hypertension in Dahl salt-sensitive rats.
abstract: Experiments were conducted to test the hypothesis that chronic administration of an opioid receptor antagonist, naloxone, would affect the outcome of the developmental phase of hypertension in Dahl salt-sensitive (S/JR strain) rats. Accordingly, S/JR rats were maintained on either a low-salt (0.45% NaCl) or a high-salt (7% NaCl) diet for 4 wk. Half of the animals of each dietary group were treated with naloxone (100-130 micrograms/h) by osmotic minipump. Food and water intakes of the high-salt animals were measured for the first 25 days, and blood pressure was measured at the end of the 4 wk via an indwelling femoral arterial catheter. Naloxone treatment slightly but significantly reduced the level of hypertension attained in the high-salt animals (158 +/- 2 mmHg in naloxone-treated animals vs. 168 +/- 3 mmHg in control animals; P less than 0.05) and also attenuated food (and hence salt) and water intakes. Naloxone did not affect the blood pressure of the low-salt animals. To determine whether the slight attenuation of hypertension might be secondary to a reduction of salt intake, a group of control S/JR animals were fed a moderately high-salt diet (2% NaCl), and naloxone-treated S/JR animals were salt-intake matched to this group by daily adjustment of the dietary salt content. Blood pressures after 4 wk of treatment were not different between these two groups. Finally, acute administration of 1 and 30 mg/kg of naloxone failed to lower blood pressure of animals with established hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology, West Virginia University Health Sciences Center, Morgantown 26506.
authors.forename: M D
authors.initials: MD
authors.lastname: Johnson
authors.forename: B K
authors.initials: BK
authors.lastname: Richmond
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D004032:Diet; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009020:Morphine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D011922:Rats, Mutant Strains; D012965:Sodium Chloride / Q000008:administration & dosage
chemical_list: D009270:Naloxone; D012965:Sodium Chloride; D009020:Morphine