TY - JOUR
T1 - Functional expression of adrenergic and opioid receptors in Xenopus oocytes
T2 - interaction between α2- and β2-adrenergic receptors
AU - Birnbaum, Angela K.
AU - Wotta, Diane R.
AU - Law, Ping Y.
AU - Wilcox, George L.
PY - 1995/1
Y1 - 1995/1
N2 - We functionally expressed α2-adrenergic, β2-adrenergic, and δ-opioid receptors in Xenopus laevis oocytes. We detected receptor function as changes in currents carried by adenosine 3′,5′-cyclic monophosphate (cAMP)-regulated chloride channels provided by the cystic fibrosis transmembrane conductance regulator (CFTR) and recorded by two-electrode voltage clamp. Co-application of forskolin and isobutylmethylxanthine (IBMX) or IBMX alone produced currents with a reversal potential indicative of chloride ions only in oocytes previously injected with mRNA encoding CFTR. Isoproterenol produced concentration-dependent responses in oocytes injected with mRNA encoding β2-adrenergic receptors and CFTR, and co-administration of propranolol antagonized these responses. Similarly, the α2-adrenergic agonist UK14304 increased IBMX-induced currents only in oocytes injected with mRNA encoding α2-adrenergic receptors and CFTR, and idazoxan antagonized these enhancements. The δ-opioid agonist DADLE produced concentration-related, naloxonc-reversible increases in IBMX- and forskolin-induced currents only in oocytes injected with mRNA encoding δ-opioid receptors and CFTR. In oocytes co-injected with α2, β2, and CFTR mRNAs, isobolographic analysis revealed an additive interaction between α2 - and β2-adrenergic receptors. These studies establish the oocyte as a cell system for studying the interactions among cAMP-modulating G protein-coupled receptors and provide another example of alternative coupling of α2-adrenergic and δ-opioid receptors to G proteins, possibly Gs proteins, other than Gi proteins.
AB - We functionally expressed α2-adrenergic, β2-adrenergic, and δ-opioid receptors in Xenopus laevis oocytes. We detected receptor function as changes in currents carried by adenosine 3′,5′-cyclic monophosphate (cAMP)-regulated chloride channels provided by the cystic fibrosis transmembrane conductance regulator (CFTR) and recorded by two-electrode voltage clamp. Co-application of forskolin and isobutylmethylxanthine (IBMX) or IBMX alone produced currents with a reversal potential indicative of chloride ions only in oocytes previously injected with mRNA encoding CFTR. Isoproterenol produced concentration-dependent responses in oocytes injected with mRNA encoding β2-adrenergic receptors and CFTR, and co-administration of propranolol antagonized these responses. Similarly, the α2-adrenergic agonist UK14304 increased IBMX-induced currents only in oocytes injected with mRNA encoding α2-adrenergic receptors and CFTR, and idazoxan antagonized these enhancements. The δ-opioid agonist DADLE produced concentration-related, naloxonc-reversible increases in IBMX- and forskolin-induced currents only in oocytes injected with mRNA encoding δ-opioid receptors and CFTR. In oocytes co-injected with α2, β2, and CFTR mRNAs, isobolographic analysis revealed an additive interaction between α2 - and β2-adrenergic receptors. These studies establish the oocyte as a cell system for studying the interactions among cAMP-modulating G protein-coupled receptors and provide another example of alternative coupling of α2-adrenergic and δ-opioid receptors to G proteins, possibly Gs proteins, other than Gi proteins.
KW - Adenylyl cyclase
KW - CFTR
KW - Cystic fibrosis transmembrane conductance regulator
KW - Protein kinase A
KW - cAMP
KW - α Adrenoceptor
KW - β Adrenoceptor
KW - δ Opioid receptor
UR - http://www.scopus.com/inward/record.url?scp=0028877833&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028877833&partnerID=8YFLogxK
U2 - 10.1016/0169-328X(94)00185-H
DO - 10.1016/0169-328X(94)00185-H
M3 - Article
C2 - 7707880
AN - SCOPUS:0028877833
SN - 0169-328X
VL - 28
SP - 72
EP - 80
JO - Molecular Brain Research
JF - Molecular Brain Research
IS - 1
ER -