Adrenergic alpha-Agonists/metabolism; Adrenergic alpha-Antagonists/metabolism; Receptors, Adrenergic, alpha/chemistry; Amino Acid Sequence; Animals; Base Sequence; Binding Sites; Blotting, Northern; Cattle; Cell Line; Clonidine/analogs & derivatives; Clonidine/pharmacology; Cloning, Molecular; DNA, Complementary/chemistry; DNA, Complementary/genetics; Enzyme Activation/drug effects; Gene Expression/genetics; Glycosylation; Humans; Molecular Sequence Data; Oligonucleotide Probes; Open Reading Frames; Phosphorylation; RNA, Messenger/analysis; Rats; Receptors, Adrenergic, alpha/classification; Receptors, Adrenergic, alpha/drug effects; Receptors, Adrenergic, alpha/genetics; Ribonucleases/chemistry; Sequence Alignment; Sequence Homology, Amino Acid; Type C Phospholipases/metabolism