Sodium and volume depletion activates neurogenic mechanisms in renal hypertensive dogs.
The acute response to ganglionic blockade (hexamethonium bromide, 30 mg/kg, i.v.) was used to evaluate the neurogenic contributions to mean arterial pressure maintenance in the conscious one-kidney, one clip hypertensive dog. Approximately 2 hours (112 minutes) after ganglionic blockade, captopril (10 mg/kg, i.v.) was given to block the renin-angiotensin system. Hypertensive animals were studied 3 days after clipping (group 2) or 2 to 4 weeks after clipping (groups 3 and 4). Groups 2 and 3 were fed a regular sodium diet, but group 4 animals were sodium and volume depleted. Normotensive control animals (group 1) were fed a regular sodium diet. On the day of the acute experiment the baseline blood pressures measured in group 2 (151 +/- 10 mm Hg, n = 5), group 3 (154 +/- 5 mm Hg, n = 7), and group 4 (160 +/- 8 mm Hg, n = 7) were not different (p greater than 0.05) from each other, but all were elevated (p less than 0.05) compared with the group 1 animals (106 +/- 3 mm Hg, n = 8). Also, there were no significant differences (p greater than 0.05) in the baseline plasma catecholamine levels among the three hypertensive groups. Ganglionic blockade produced a greater fall in blood pressure (p less than 0.05) in the sodium/volume-depleted dogs of group 4 (-35 mm Hg) than in group 1 (-10 mm Hg), group 2 (-3 mm Hg), or group 3 (-12 mm Hg) animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Sweet
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Freeman
R H
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Davis
J O
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Villarreal
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D000818:Animals; D002216:Captopril / Q000494:pharmacology; D002395:Catecholamines / Q000502:physiology; D004285:Dogs; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D006978:Hypertension, Renovascular / Q000503:physiopathology*; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System; D012964:Sodium / Q000378:metabolism*
D002395:Catecholamines; D006584:Hexamethonium Compounds; D018738:Hexamethonium; D002216:Captopril; D012964:Sodium; D012083:Renin