Table 1.

The distribution and stability of HB-19 in target organs from rats injected with [³H]-labeled HB-19

Organ	Total HB-19 counts, %/gm tissue	Intact HB-19 (of the % retained)
Spleen	1.2%/1.0%	37.7%/36.2%
Thymus	0.6%/0.5%	31.7%/32.0%
Liver	24.4%/23.2%	21.5%/22.9%
Kidney	3.1%/3.4%	16.0%/17.7%

The two values in each column correspond to rat 1 and rat 2, respectively. Two rats were injected intravenously with [³H]-labeled HB-19 (20 μg; 1.8 MBq) and killed at 24 h. In order to estimate the presence of intact HB-19, the tissue extracts were assessed for RP-HPLC analysis (Materials and Methods). The total tritium activity was determined as counts per minute per gram of tissue. The % of total HB-19-associated tritium radioactivity within target organs represented the amount radioactivity quantified per organ in respect to the total radioactivity injected. The % of intact (undegraded) HB-19 in different tissues represented the amount of radioactivity quantified in the HB-19 HPLC peak with respect to the total radioactivity in each organ.