Distribution and subtype determination ofβ-receptors in the spinal cord of the adult rat
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We determined the number ofβ-receptors in the whole spinal cord of the adult rat and in the cervical, thoracal, and lumbal/sacral parts.
The undivided spinal cord contains 47 ± 10 fmol/mgβ-receptors (KD = 2066 ± 982 pmol/liter), and the cervical part of the spinal cord contains 53 ± 8 fmol/mg protein (KD = 3224 ± 1775 pmol/liter). The thoracal part shows 40 ± 1 fmol/mg protein (KD = 3229 ± 104 pmol/liter), and the lumbal/sacral spinal cord contains 48 ± 8 fmol/mg protein (KD = 3610 ± 1610 pmol/liter).
Competitive inhibition studies withl-practolol,dl-atenolol, and ICI 118,551 were performed and we calculated by a computer program in the whole spinal cord the following ratio ofβ-receptor subtypes: 80 ± 5%β1-receptors and 20 ± 5%β2-receptors.
The basal and (−)-isoproterenol- and NaF-stimulated activity of adenylate cyclase was highest in the cervical part of the spinal cord and equally distributed between the thoracal and the lumbal/sacral parts.
The whole synaptosomal protein of the cervical part of the spinal cord contained 132 ± 20 fmol, the thoracal part 117 ± 3 fmol, and the lumbal/sacral part 133 ± 22 fmol.
Key wordsspinal cord adult rat subtype β-adrenergic receptor
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