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. 2008 May 7;295(1):R343–R354. doi: 10.1152/ajpregu.00115.2008

Fig. 2.

Fig. 2.

Effect of sequential transections of the neuraxis on the activity of tail CVC postganglionic neurons. A: top image illustrates the approximate positions of serial (rostral-to-caudal) transections of the neuraxis by vertical lines (labeled as distance caudal to bregma) superimposed on a drawing of the rat brain (44). Traces, time courses of the mean arterial pressure (MAP) and the action potential frequency of two discriminated tail CVC neurons (insets: average of 150 discriminated action potentials; vertical scale: 20 μv; horizontal scale: 2 ms). Phenylephrine (PE)-induced increase in MAP (+90 mmHg from 94 mmHg) elicited a baroreceptor-mediated inhibition of the discharge of the CVC neurons (trace a). Horizontal scale: 10 min. Oscillographic traces of unit action potentials (a–c) are 1 min duration, vertical scale: 20 μv. POA, preoptic area; rRPa, rostral raphé pallidus; Th, thalamus; Dk, nucleus of Darkschewitsch; 3: occulomotor nucleus. B: mean ± SE CVC neuronal discharge frequency following serial transections of the neuraxis. Open hatched bar indicates pretransection firing frequency. *Significant (P < 0.05) increase above pretransection level resulting from cut at bregma −2 mm (caudal to the POA). After transections at bregma −4 or −6 mm, mean CVC neuronal activity was not different from that after transection at bregma −2 mm. Transection at bregma −13 mm (caudal to the rRPa) significantly reduced CVC neuronal activity (solid bracket: P < 0.01). Hexamethonium eliminated CVC neuronal activity (dashed bracket: P < 0.05).