Kurahashi K, Akimoto Y, Usui H, Jino H
Pharmacology Division, Kyoto University, Japan.
Life Sci. 1992;51(9):695-702. doi: 10.1016/0024-3205(92)90243-i.
Nifedipine-resistant Ca(++)-induced contractions (NR-Ca(++)-contraction) were compared in the tail arteries from SHRs and WKYs (5 and 13 week old). NR-Ca(++)-contraction of tail artery was defined as follows: Ca(++)-induced contraction in the presence of norepinephrine (NE) (10(-5) M) or 5-hydroxytryptamine (5-HT) (10(-5) M) in Ca(++)-free medium containing EGTA (0.1 mM) and nifedipine (10(-6) M). NR-Ca(++)-contractions in arteries from 5 week old SHRs and WKYs were not different. In contrast, NR-Ca(++)-contractions in arteries from 13 week old SHRs were about 2-fold greater than in arteries from 13 week old WKYs. In arteries from 13 week old WKYs and SHRs, nitroglycerin (10(-5) M) significantly reduced the NR-Ca(++)-contraction in the presence of 5-HT but not in the presence of NE. The reduction was inhibited by the presence of methylene blue (3 x 10(-6) M). 8-Bromo-cGMP (10(-4) M) reduced significantly the NR-Ca(++)-contraction in the presence of 5-HT in arteries from 13 week old SHRs and WKYs. The present experiments clearly demonstrated that the NR-Ca(++)-contractions (both in the presence of NE and 5-HT) in 13 week old SHRs were significantly greater than those in arteries from 13 week old WKYs. These results suggest that in addition to an increase in voltage-operated Ca++ mobilization reported by others, an increase in NR-Ca++ mobilization may contribute to the development of hypertension in SHR.
比较了自发性高血压大鼠（SHRs）和Wistar-Kyoto大鼠（WKYs）（5周龄和13周龄）尾动脉中硝苯地平抵抗性Ca(++)诱导的收缩（NR-Ca(++)收缩）。尾动脉的NR-Ca(++)收缩定义如下：在含有乙二醇双四乙酸（EGTA）（0.1 mM）和硝苯地平（10(-6) M）的无Ca(++)培养基中，去甲肾上腺素（NE）（10(-5) M）或5-羟色胺（5-HT）（10(-5) M）存在时Ca(++)诱导的收缩。5周龄SHRs和WKYs动脉中的NR-Ca(++)收缩无差异。相反，13周龄SHRs动脉中的NR-Ca(++)收缩比13周龄WKYs动脉中的约大2倍。在13周龄WKYs和SHRs的动脉中，硝酸甘油（10(-5) M）在5-HT存在时显著降低NR-Ca(++)收缩，但在NE存在时则不然。亚甲蓝（3×10(-6) M）存在时可抑制这种降低。8-溴环鸟苷酸（10(-4) M）在13周龄SHRs和WKYs动脉中5-HT存在时显著降低NR-Ca(++)收缩。本实验清楚地表明，13周龄SHRs中的NR-Ca(++)收缩（在NE和5-HT存在时）显著大于13周龄WKYs动脉中的收缩。这些结果表明，除了其他人报道的电压依赖性Ca++动员增加外，NR-Ca++动员增加可能也有助于SHR高血压的发展。
