Table 1.

Cardiac function in response to isoproterenol and tyramine

		Saline (n=8)	Propranolol (n=8)
Resting	HR, bpm	400 ± 14	411 ± 13
	ESP, mmHg	124 ± 12	131 ± 10
	EDP, mmHg	7.7 ± 2.8	4.0 ± 0.5
	Peak dP/dtmax, mm Hg/s	11808 ± 1275	14497 ± 825
	Peak dP/dtmin, mm Hg/s	8229 ± 788	9081 ± 709
Chlorisondamine	HR, bpm	342 ± 10	350 ± 8
	ESP, mmHg	60 ± 3	68 ± 4
	EDP, mmHg	6.9 ± 0.9	4.8 ± 0.4
	Peak dP/dtmax, mm Hg/s	2169 ± 145	2705 ± 196*
	Peak dP/dtmin, mm Hg/s	2131 ± 263	3335 ± 380*
Isoproterenol	HR, bpm	461 ± 12	479 ± 11
	ESP, mmHg	88 ± 5	93 ± 5
	EDP, mmHg	3.9 ± 0.7	2.5 ± 0.4
	Peak dP/dtmax, mm Hg/s	8476 ± 739	9552 ± 297
	Peak dP/dtmin,, mm Hg/s	4894 ± 476	5731 ± 779
Tyramine	HR, bpm	434 ± 17	458 ± 16
	ESP, mmHg	83 ± 3	103 ± 8*
	EDP, mmHg	4.9 ± 0.7	2.9 ± 0.5*
	Peak dP/dtmax, mm Hg/s	8081 ± 688	10922 ± 581**
	Peak dP/dtmin, mm Hg/s	5427 ± 622	6881 ± 696

Responses obtained 48 h after discontinuation of a 7 day infusion of saline or propranolol. Values were obtained in the resting state under urethane anesthesia, following ganglionic blockade with chlorisondamine, and after a maximally effective dose of the direct β agonist isoproterenol, or displacement of sympathetic norepinephrine stores by a maximal dose of tyramine. Results are presented as the mean ± s.e.m.

^*P<0.05 compared to saline infusion,

^**P<0.01.