1990 Fiscal Year Final Research Report Summary
The Role of Carbohydrate Moiety in Alpha_1-adrenoceptors in Rat Heart : Composition with those of Beta_1-adrenoceptors (1988-1989).
| Project/Area Number |
63570102
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General pharmacology
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| Research Institution | Nigata University of Phermacy and Applied Life Sciences |
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Principal Investigator |
NAGATOMO Takafumi Niigata College of Pharmacy, Professor, 薬学部・薬理学教室, 教授 (60121240)
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| Co-Investigator(Kenkyū-buntansha) |
MARUYAMA Keiko Niigata College of Pharmacy, Technical Assistant, 薬理学教室, 技術員 (30219563)
TSUCHIHASHI Hiroshi Niigata College of Pharmacy, Instructor, 薬理学教室, 講師 (50155397)
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| Project Period (FY) |
1988 – 1989
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| Keywords | alpha_1-Adrenoceptors / beta_1-adrenoceptors / Heart muscle membrane / ^3H-prazosin / ^3HーCGP12177 / Heparin / Polymixin B / DNA |
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| Research Abstract |
The present study was designed to test the role of carbohydrate moiety in the alpha_1-adrenoceptors in rat heart membranes using the radioligand binding assay. The rat hearts were used and ^3H-prazosin and ^3H-CGP12177 were used as radioligands. Kd values of alpha_1- and beta_1-adrenoceptors obtained from Scatchard analysis using l ligand-l receptor model were 0.493<plus-minus>0.305 (alpha_1-) and 0.502<plus-minus>0.135 (beta_1-) nM, and in addition, Bmax values of those receptors were 29.8<plus-minus>18.8 (alpha_1-) and 9.0<plus-minus>0.9 (beta_1-) fmole/mg protein, respectively. The result obtained Scatchard analysis using l-ligand-2 receptor model showed biphasic curves and this implies that two binding sites of ^3H-prazosin in rat heart membrane were existed.
The effect of polymeric effectors (polymixin B, heparin and DNA) on the ^3H-prazosin and ^3H-CGP12177 bindings to alpha_1-adrenoceptor and beta_1-adrenoceptors in rat heart membrane was also examined. Although no changes in values of Kd and Bmax of alpha_1-adrenoceptors by addition of these polymeric effectors in vitro was observed, polymixin B induced the high Kd values and heparin induced high Bmax values of beta_1-adrenoceptors of rat heart membranes. No changes in beta-adrenoceptors by the addition of DNA were observed.
In conclusion, the present study suggest that different binding characteristics of each adrenoceptor may exist from results of the different effects of polymeric effectors. In addtion, the results obtained from rat heart muscle was different from these of rat brain. Thus, binding charaacteristics of alpha_1- and beta_1-adrenoceptors in rat heart may be different from those in brain.
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