TABLE 2.

Average concentrations in discs of varied thicknesses at t = 2 min

Volume of disc or chamber μl	Surface area of disc cm2	Estimated thickness of disc or chamber μm	Gidday et al. observations	Constant source
				No subepicardial layer		Subepicardial layer of thickness
						100 μm	200 μm
			$\frac{C_{2\min }}{C_{\infty }^{\ast }}$	*Dt/l2	$\frac{C_{2\min }}{C_{\infty }^{\ast }}$	$\frac{C_{2\min }}{C_{\infty }^{\ast }}$	$\frac{C_{2\min }}{C_{\infty }^{\ast }}$
0	-	0	1.00	-	1.00	1.00	1.00
4.8	0.64	113†	1.00	8.10	1.00	1.00	0.94
9.5	0.64	226†	1.12	2.02	0.99	0.93	0.80
17.0	0.64	400†	0.47	0.64	0.83	0.71	0.61
25.0	0.64	589†	0.35	0.50	0.62	0.52	0.46
100.0	1.00	1000	0.08	0.10	0.36	0.34	0.30

*Dt/l² shown only for the case with the source at the epicardial surface. $C_{\infty }^{\ast }$ represents the concentration in the thinnest epicardial disc at two minutes; C∞ for the calculations represents the equilibrium value.

† assumes disc matrix fractional volume of one third.