Table 4.

Cardiopulmonary chemoreflex responses to PBG (1–8 µg/kg) evoxed under control conditions (control), compared to the responses evoked after microinjection into the NTS of A_2a receptor agonist (CGS 21680, 20 pmol/50 nl) and similar comparison performed after blockade of NTS A2a receptors with equimolar microinjections of the selective antagonist, ZM-241385 (40 pmol/100 nl).

		Control					CGS 21680
Number of animals	PBG µg/kg	MAP Δ%	HR Δbpm	RSNA Δ%	pre- ASNA Δ%	LSN A Δ%	MAP Δ%	HR Δbpm	RSN A Δ%	pre- ASNA Δ%	LSNA Δ%
9	1	−11 ± 2	−11 ± 3	−36.7 ± 7.2	−27.8 ± 7.2	−23.4 ± 4.3	−5 ± 1*	−11.3 ± 4.8	−12.6 ± 3.9*	−11.9 ± 3.9*	−8.5 ± 1.8*
	2	−21 ± 2	−25 ± 5	−73.6 ± 4.1	−51.1 ± 7.6	−49.2 ± 4.6	−5 ± 1*	−9.3 ± 1.7*	−24.7± 7.3*	−11.8 ± 1.8*	−10.8 ± 2.0*
	4	−25 ± 2	−48 ± 9	−89.8 ± 3.0	−65.2 ± 5.5	−58.3 ± 3.8	−9 ± 2*	−13.4 ± 2.0*	−35.9 ± 5.4*	−24.8 ± 3.2*	−21.4 ± 3.6*
	8	−33 ± 2	−85 ± 19	−95.5 ± 1.4	−74.4 ± 6.4	−60.2 ± 4.0	−17 ± 2*	−28.4 ± 4.5*	−57.8 ± 4.7*	−41.7 ± 7.9*	−38.7 ± 5.3*

		Control					ZM 241385 + CGS 21680
	PBG µg/kg	MAP Δ%	HR Δbpm	RSNA Δ%	pre- ASNA Δ%	LSN A Δ%	MAP Δ%	HR Δbpm	RSN A Δ%	pre- ASNA Δ%	LSNA Δ%
6	1	−16 ± 3	−34 ± 20	−54.3 ± 9.2	−43.9 ± 16.9	−23.6 ± 3.7	−13 ± 3#	−26 ± 9	−36.8 ± 6.8#	−40.3 ±13.0#	−20.0 ± 2.1#
	2	−25 ± 2	−34 ± 13	−81.3. ± 4.3	−64.5 ± 9.8	−41.8 ± 3.7	−19 ± 5#	−32 ± 6#	−69.7 ± 9.6#	−60.0 ± 14.3#	−29.6 ± 3.9#
	4	−30 ± 3	−88 ± 35	−87.9 ± 3.0	−75.0 ± 7.7	−43.8 ± 4.6	−27 ± 5#	−74 ± 20#	−87.3 ± 3.2#	−59.8 ± 11.0#	−38.7 ± 0.1
	8	−39 ± 3	−146 ± 45	−90.8 ± 2.4	−84.5 ± 5.0	−44.1 ± 4.3	−35 ± 6#	−128 ± 41 #	−91.0 ± 2.3#	−74.1 ± 8.2#	−38.9 ± 3.3

Values are mea ns ± SE. PBG, phenylbiguanide,

^*, P<0.05 vs. control,

^#, P<0.05 differences between two groups of animals. Note that blockade of NTS A2a adenosine receptors (lower panel) abolished the inhibition of the reflex responses caused by selective activation of these receptors with the highest dose of the agonist (CGS 21680, 20 pmpl/50 nl) (upper panel).