The Effect of Papaverine on the Calcium-dependent K+ Current in Rat Basilar Smooth Muscle Cells

OBJECTIVE: Papaverine has been used in treating vasospasm following subarachnoid hemorrhage(SAH). However, its action mechanism for cerebral vascular relaxation is not clear. Potassium channels are closely related to the contraction and relaxation of cerebral smooth muscle. Therefore, to identify the role of potassium and calcium channels in papaverine-induced vascular relaxation, we examine the effect of papaverine on potassium channels in freshly isolated smooth muscle cells from rat basilar artery. METHODS: The isolation of rat basilar smooth muscle cells was performed by special techniques. The whole cell currents were recorded by whole cell patch clamp technique in freshly isolated smooth muscle cells from rat basilar artery. Papaverine was added to the bath solution. RESULTS: Papaverine of 100 microM into bath solution increased the amplitude of the outward K+ current which was completely blocked by BKCa(large conductance calcium dependent potassium channels)blocker, IBX(iberiotoxin), and calcium chealator, BAPTA(1, 2-bis(o-aminophenoxy)ethane-N, N, N', N'-tetraacetic acid), in whole cell mode. CONCLUSION: These results strongly suggest that potassium channels may play roles in papaverine-induced vascular relaxation in rat basilar artery.

Effects of Tyrosine Kinase Inhibitors on the Calcium-Dependent K+ Current in Rat Basilar Smooth Muscle Cells

OBJECTIVE: Tyrosine kinase inhibitors may be useful in the management of cerebral vasospasm. It has not yet reported whether potassium channel plays a role in tyrosine kinase inhibitors-induced vascular relaxation of cerebral artery. This study is undertaken to clarify the role of potassium channel in tyrosine kinase inhibitors-induced vascular relaxation, and to investigate the effect of tyrosine kinase inhibitors on outward potassium currents in freshly isolated smooth muscle cells from rat basilar artery. METHODS: The isolation of rat basilar smooth muscle cells was performed by special techniques. The whole cell currents were recoreded by whole cell patch clamp technique in freshly isolated smooth muscle cells from rat basilar artery. RESULTS: In present study, genistein(n=10), tyrphostin A-23(n=10), A-25(n=10) 30microM into bath solution increased the amplitude of the outward K+ current which was completely blocked by large conductance calcium-activated potassium channel(BK(Ca)) blocker, iberiotoxin(0.1microM), and calcium chelator, BAPTA, in whole cell mode. In contrast, diadzein 30microM(n=10), inactive analogue of genistein, did not increase the amplitude of the outward K+ current. CONCLUSION: Our results suggest tyrosine kinase inhibitors such as genistein, tyrphostin A-23 and A-25 increase the BK(Ca) channel activity in cerebral basilar smooth muscle cells, thereby contributing to the relaxation of cerebral artery.

The Effect of Papaverine on L-Type Ca2+ Current in Rat Basilar Smooth Muscle Cells

OBJECTIVE: Papaverine has been used to manage vasospasm after subarachnoid hemorrhage. However, its mechanism for cerebrovascular smooth muscle are still not clear. This study was undertaken to investigate the effect of papaverine on L-type Ca2+ channels directly by using patch clamp techniques in freshly isolated single smooth muscle cells from rat basilar artery. METHODS: Whole-cell patch clamp technique was used for measuring the amplitude of L-type Ca2+ current. Papaverine was added to the bath solution. RESULTS: Patch clamp studies revealed a whole-cell current which resembles the L-type Ca2+ current reported by others. The amplitude of this current was decreased by nimodipidine and increased by Bay K 8644. Papaverine 100 micro M reduced the amplitude of the L-type Ca2+ channel current. CONCLUSION: We can conclude that papaverine may relax cerebral vessel through decreasing level of intracellular calcium, [Ca2+]i, by inhibition of L-type Ca2+ channel.

Cavernous Hemangioma of the Cauda Equina

Spinal cavernous hemangiomas of the cauda equina are extremely rare vascular malformations. We report a case of intradural extramedullary cavernous hemangioma of the cauda equina with it's clinical, radiologic and surgical findings. This is the twelveth case of cavernous hemangioma of the cauda equina in the literature. The pertinent literatures are reviewed.

Results of Microsurgical Anterolateral Tunnel Approach for Cervical Disc Herniation

OBJECTIVE: The authors report the microsurgical anterolateral tunnel approach for the treatment of the cervical disc diseases and its postoperative surgical results. METHODS: All surgical procedures followed the method of classical microsurgical anterior discectomy. Small tunnel(7-8mm) was made on the disc space reaching to the posterior longitudinal ligament. The disc materials and bony spurs were removed through this tunnel. Thirty-one patients of cervical disc herniation(24 cases with pure disc herniation, 7 cases with combined cervical spondylosis) were evaluated on the symptoms, conformation in plain X-ray, C-T, and MRI. The follow up time was over 2 years . RESULTS: Postoperatively the result(following the out come scale) was excellent and good in Twenty-nine patients. One with fair result showed remnant disc particle and spur and another one is combined with cord contusion. One patient with lesion in C 3-4 space and two cervicothoracic junction showed excellent result. Two patients with osteoporosis also showed good results. Cervical spine curvature and disc space height were not changed on the plain X-ray and MRI in all patients. Twenty-nine patients were discharged within 3 days after surgery without any postoperative complications. CONCLUSIONS: The microsurgical anterolateral tunnel approach could be indicated for the treatment of patients with cervical disc diseases and with difficulty in achieving interbody fusion(the higher cervical level and cervicothoracic junction, osteoporosis etc.).