en The Role of Ca2+ and K+ channels in regulation the pattern of spontaneous activity in cerebellar Purkinje cells. Experimental research article Experimental research article <b><font face="TimesNewRomanPS-BoldMT" size="4"><p align="left">The Role of Ca2+ and K+ channels in regulation the pattern of spontaneous activity</p><p align="left">in cerebellar Purkinje cells.</p></font><font face="TimesNewRomanPS-BoldMT" size="2"><p align="left">H Haghdoost Yazdi, M Janahmadi and G Behzadi</p></font><i><font face="TimesNewRomanPS-BoldItalicMT" size="2"><p align="left">Dept. Physiology and Neuroscience Research Center, School of Medicine,</p><p align="left">Shaheed Beheshti Univ. Med. Sci., Tehran, Iran.</p></font><font face="TimesNewRomanPS-BoldMT" size="3"><p align="left">Abstract:</p></font><font face="TimesNewRomanPSMT" size="3"><p align="left">The cerebellum is responsible for coordination of movement and maintenance of balance. Purkinje cells (PCs) are</p><p align="left">principle neurons of anatomically well defined cerebellar modules and it is proposed that coordination of movement</p><p align="left">is achieved by encoding timing signals in the rate of firing and pattern of activity these cells. Understanding of</p><p align="left">cerebellar timing requires an appreciation of the intrinsic firing behavior of PCs.</p><p align="left">In order to determine how changes in membrane biophysics including Ca2+ and K+ channels activity influence</p><p align="left">the electrical activity of Purkinje neurons, intracellular recording from acutely prepared cerebellar slices was</p><p align="left">performed. PCs fired spontaneously bursts of calcium or sodium-calcium spikes which were separated by</p></font><font face="TimesNewRomanPSMT" size="4"><p align="left">1</p></font><font face="TimesNewRomanPSMT" size="1"><p align="left">Physiology and Pharmacology<font face="TimesNewRomanPSMT" size="3"></font><b><font face="TimesNewRomanPS-BoldMT" size="3"><p align="left">Keywords: </p></font><font face="TimesNewRomanPSMT" size="3">Purkinje Neurons, Firing Pattern, Brain Slices, Intracellular Recording, Apamin, DTX</font></b></p><p align="left">quiescent- interburst periods. They also showed long lasting bursts and long silence periods. Cadmium, a wild</p><p align="left">range of Ca2+ channels blocker, resulted in an elimination of calcium spikes while left the sodium action potential</p><p align="left">intact. Blockade potassium channels by 4-AP and TEA improved the spontaneous activity and limited silence</p><p align="left">period. 4-AP also prolonged the burst and interburst period and decreased the firing frequency. On the other</p><p align="left">hand, apamin, a neurotoxin from bee venom, known to selectively block small conductance of calcium activated</p><p align="left">potassium channels (SK), and α-dendrotoxin (DTX), specific blocker of Kv1 channels, shortened the burst</p><p align="left">and interburst duration. DTX and apamin also increased the frequency of burst occurrence and DTX decreases</p><p align="left">intraburst frequency.</p><p align="left">In conclusion, with the data presented it is fair to state that intrinsic membrane properties including K+ channels</p><p align="left">activity, seem to play important roles in the formation of firing patterns in Purkinje neurons.</p></font></i></b> 107 114 http://ppj.phypha.ir/browse.php?a_code=A-10-25-1&slc_lang=en&sid=1