. 2019 Oct;71(4):467–502. doi: 10.1124/pr.119.017533

TABLE 6.

Apelin isoforms have comparable potencies at the apelin receptor expressed on cardiomyocytes, vascular endothelial and smooth muscle cells from human isolated cardiovascular tissue

EC₅₀ values are geometric means. Values are mean ± S.E.M.

Action	[Pyr¹]Apelin-13			Apelin-13			Apelin-36
	EC₅₀	pD₂	E_MAX	EC₅₀	pD₂	E_MAX	EC₅₀	pD₂	E_MAX
Inotropy^a	0.1	9.9 ± 0.2	49%	0.08	10.1 ± 0.3	64%	0.04	10.4 ± 0.2	39%
Vasodilatation^b	1.6	8.8 ± 0.1	39%	0.6	9.2 ± 0.2	51%	0.8	9.1 ± 0.2	43%
Vasoconstriction^c	1.6	8.8 ± 0.5	30%	0.8	9.1 ± 0.2	19%	0.6	9.2 ± 0.5	17%

EC₅₀, the concentration (nmol/l) of apelin peptide producing 50% of the maximum response to that peptide; E_MAX, maximum response, expressed as a % of a reference stimulus; pD₂, negative log₁₀ EC₅₀.

^{^a}

Human, electrically paced atrial strip. Maximum response is % inotropic response to calcium (8.95 mmol/l).

^{^b}

Endothelium-dependent vasodilatation in human mammary artery pre-constricted with ET-1. Maximum response (E_MAX) is % reversal of ET-1 response.

^{^c}

Contraction of endothelium-denuded saphenous vein. Maximum response (E_MAX) is %KCL (100 mmol/l). Tissues were maintained in organ baths at 37°C in oxygenated physiologic saline (Maguire et al., 2009).