Divergent action of verapamil perfused in two hypothalamic areas on body temperature of the cat.
Guide cannulae for push-pull perfusion were bilaterally implanted stereotaxically within the anterior hypothalamic, preoptic area (AH/POA) and posterior hypothalamus (PH) of the cat. Catecholamine-reactive sites were identified within AH/POA in which a microinjection of norepinephrine (NE) (5.0 micrograms) evoked a characteristic, transient hypothermia. Similarly the cation-reactive region within the PH was identified in which excess Ca2+ (25 mM) also evoked a hypothermic response. When verapamil was perfused at a rate of 25.0 microliters/min in a concentration of 0.4 or 2.0 micrograms/microliter within AH/POA at a NE-sensitive site, a concentration-dependent decline in the core temperature of the cat occurred. Conversely, verapamil perfused in the same manner with a Ca2+-reactive site caused an intense rise in the cat's body temperature which also was concentration dependent. These results show that the localized blockade of slow Ca2+ channels exerts direct, differential physiological effects within central nervous system tissue. In this case, verapamil mimics noradrenergic effects within the AH/POA; however, the hyperthermic response following Ca2+ channel blockade within tissue of the PH resembled that produced by ethyleneglycoltetraacetic acid or Na ions.
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- Verapamil
- Preoptic Area
- Hypothalamus, Posterior
- Hypothalamus
- Cats
- Body Temperature
- Animals
- 5202 Biological psychology
- 3209 Neurosciences
- 3101 Biochemistry and cell biology
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Verapamil
- Preoptic Area
- Hypothalamus, Posterior
- Hypothalamus
- Cats
- Body Temperature
- Animals
- 5202 Biological psychology
- 3209 Neurosciences
- 3101 Biochemistry and cell biology