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Clonidine-Induced Heat-Shock Protein Expression in Rat AortaDepartment of Pharmocology and Toxicology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota
Department of Pharmocology and Toxicology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota
Department of Pharmocology and Toxicology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota
Department of Pharmocology and Toxicology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota Background: Restraint-stress and administration of drugs that precipitate hypertension induce heat-shock protein (HSP) expression in the aorta. The exact mechanism supporting this hypertension-related HSP response is unclear because HSP induction is blocked by receptor-selective and nonselective antihypertensive agents.
Methods and Results: To identify mechanisms contributing to the pharmacological/physio logical regulation of the HSP response in cardiovascular tissues, we administered clonidine to awake and freely moving animals to determine its effect on HSP expression in vivo. Inconsistent with previous work, we found that clonidine produced a dose-dependent and transient increase in HSP70 mRNA levels in the aorta. No other tissue examined displayed an HSP response after clonidine administration. Clonidine-induced HSP expression was not restricted to the HSP70 family; HSP89 Conclusions: The functional consequence of HSP expression in cardiovascular tissues may be to alter the responsiveness of cells in these tissues to subsequent drug or stress exposures, thereby implicating the HSP response as an important component of cardiovascular homeo stasis. If so, treatment of mammalian organisms with drugs capable of inducting selective HSP expression in vascular tissue may alter the progression of cardiovascular disease processes.
Key Words: hypertension • stress • cardiovascular • in vivo.
Journal of Cardiovascular Pharmacology and Therapeutics, Vol. 3, No. 2,
171-184 (1998) |
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, HSP89ß, and HSP60 were also induced. Interest ingly, no heat-shock element-binding activity was observed after clonidine administration, suggesting that unusual transcriptional regulatory mechanisms mediate this response. Yohimbine and nifedipine blocked HSP70 mRNA expression, whereas isoproterenol, mecamylamine, and reserpine had no effect.