Biomaterial Database

Disposition of metabolically labeled recombinant soluble CD4 (sT4) in male Sprague-Dawley rats following intravenous and subcutaneous administration. 1992

C B Davis, and K E Boyle, and J J Urbanski, and R T Paradysz, and K L Fong

Department of Drug Metabolism and Pharmacokinetics, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406.

Soluble CD4 (sT4) has been metabolically labeled with [3H]leucine in Chinese hamster ovary cells and purified by S Sepharose chromatography. Over 250 microCi of high specific radioactivity [3H]sT4 (42 Ci/mmol) was prepared. The radiolabeled molecule was chemically and biologically representative of the unlabeled molecule and thus appropriate for in vivo metabolic investigations. To explore the biotransformation and disposition of a recombinant protein, this uniformly labeled [3H]sT4 was administered intravenously and subcutaneously to male Sprague-Dawley rats. Following a single dose of 0.3 mg/kg, blood samples were collected for 9 days and analyzed for total radioactivity, total plasma radioactivity, trichloroacetic acid-precipitable plasma radioactivity, sT4-related plasma radioactivity (by extraction with a Sepharose-bound polyclonal anti-sT4 antibody), and plasma sT4 concentration (by an N and C terminal-specific Leu3A/OKT4 ELISA). Excreta were analyzed for total radioactivity. The pharmacokinetic profiles of intact sT4 were as expected from the results of previous studies. sT4 was cleared rapidly from plasma with an elimination t1/2 of 7 min (intravenous), and low sT4 levels were observed following subcutaneous administration. Comparison of the kinetic profiles of total radiolabel, trichloroacetic acid-precipitable radiolabel, sT4-related radiolabel, and the isolation of plasma proteins containing tritium have led to the following conclusions. One of the major metabolic pathways for [3H]sT4 was the degradation of the polypeptide to its constituent amino acids, which were subsequently incorporated into endogenous proteins. Incorporation of tritium into blood cell proteins resulted in a prolonged radiolabel blood profile (t1/2 greater than 250 hr). Following subcutaneous administration, [3H] sT4 was significantly degraded before reaching the vascular circulation.

UI	MeSH Term	Description	Entries
D007275	Injections, Intravenous	Injections made into a vein for therapeutic or experimental purposes.	Intravenous Injections,Injection, Intravenous,Intravenous Injection
D007279	Injections, Subcutaneous	Forceful administration under the skin of liquid medication, nutrient, or other fluid through a hollow needle piercing the skin.	Subcutaneous Injections,Injection, Subcutaneous,Subcutaneous Injection
D008297	Male		Males
D011994	Recombinant Proteins	Proteins prepared by recombinant DNA technology.	Biosynthetic Protein,Biosynthetic Proteins,DNA Recombinant Proteins,Recombinant Protein,Proteins, Biosynthetic,Proteins, Recombinant DNA,DNA Proteins, Recombinant,Protein, Biosynthetic,Protein, Recombinant,Proteins, DNA Recombinant,Proteins, Recombinant,Recombinant DNA Proteins,Recombinant Proteins, DNA
D001798	Blood Proteins	Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.	Blood Protein,Plasma Protein,Plasma Proteins,Serum Protein,Serum Proteins,Protein, Blood,Protein, Plasma,Protein, Serum,Proteins, Blood,Proteins, Plasma,Proteins, Serum
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D014316	Tritium	The radioactive isotope of hydrogen also known as hydrogen-3. It contains two NEUTRONS and one PROTON in its nucleus and decays to produce low energy BETA PARTICLES.	Hydrogen-3,Hydrogen 3
D015704	CD4 Antigens	55-kDa antigens found on HELPER-INDUCER T-LYMPHOCYTES and on a variety of other immune cell types. They are members of the immunoglobulin supergene family and are implicated as associative recognition elements in MAJOR HISTOCOMPATIBILITY COMPLEX class II-restricted immune responses. On T-lymphocytes they define the helper/inducer subset. T4 antigens also serve as INTERLEUKIN-15 receptors and bind to the HIV receptors, binding directly to the HIV ENVELOPE PROTEIN GP120.	Antigens, CD4,CD4 Molecule,CD4 Receptor,CD4 Receptors,Receptors, CD4,T4 Antigens, T-Cell,CD4 Antigen,Receptors, Surface CD4,Surface CD4 Receptor,Antigen, CD4,Antigens, T-Cell T4,CD4 Receptor, Surface,CD4 Receptors, Surface,Receptor, CD4,Surface CD4 Receptors,T-Cell T4 Antigens,T4 Antigens, T Cell
D017207	Rats, Sprague-Dawley	A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.	Holtzman Rat,Rats, Holtzman,Sprague-Dawley Rat,Rats, Sprague Dawley,Holtzman Rats,Rat, Holtzman,Rat, Sprague-Dawley,Sprague Dawley Rat,Sprague Dawley Rats,Sprague-Dawley Rats