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.
D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D002415:Cats; D007031:Hypothalamus / Q000187:drug effects*; D007034:Hypothalamus, Posterior / Q000187:drug effects; D011301:Preoptic Area / Q000187:drug effects; D014700:Verapamil / Q000494:pharmacology*
D014700:Verapamil