Ionotropic properties

NMD A receptors are selectively activated by A/-methyl-D-aspartate (NMD A) (182). NMD A receptor activation also requires glycine or other co-agonist occupation of an allosteric site. NMDAR-1, -2A, -2B, -2C, and -2D are the five NMD A receptor subunits known. Two forms of NMDAR-1 are generated by alternative splicing. NMDAR-1 proteins form homomeric ionotropic receptors in expression systems and may do so m situ in the CNS. Functional responses, however, are markedly augmented by co-expression of a NMDAR-2 and NMDAR-1 subunits. The kinetic and pharmacological properties of the NMD A receptor are influenced by the particular subunit composition. 

Forskolin (5-[acetyloxy]-3-ethenyldodecahydro-6,10,10b-trihydroxy-3,4a,7,7,10a-penta-methyl-[3R- 3a-4aP, SP, 6P, 6aa,10a, lOaP, 10ba -lFf-naphtho[2,l-b]pyran-l-one) [66575-29-9] M 410.5, m 229-232°, 228-233°. Recrystd from CfiH6-pet ether. It is antihypertensive, positive ionotropic, platelet aggregation inhibitory and adenylate cyclase activating properties [Chem AbstrS9 1978 244150, de Souza et al. Med Res Rev 3 201 1983]. 

Monyer H, Jonas P, Rossier J (1999) Molecular determinants controlling functional properties of AMPARs and NMDARs in the mammalian CNS, chapter 9 Ionotropic glutamate receptors in the CNS. Springer Verlag... 

Typically, a binary system was selected as the base component of the recipe and the addition of polyelectrolytes to either side (core or receiving bath) was tested to evaluate the change in the capsule properties. The 33 successful multicomponent membrane systems are presented in Table 1. The components of the core material side (21 different chemical compositions) are listed in the first column, while the receiving bath components (20 different chemical compositions) are listed in the second column. With the exception of xanthan and CMC, the first polymer listed on the core side are gelling polymers which form beads with the appropriate ionotropic cation (salt). CMC can also be gelled by ions (alum), although they are considered to be non-compatible for cellular applications. The cations were tested both sequentially, usually with ionotropic cation first, and simultaneously. Walled capsules with adequate mechanical properties were often obtained through the simultaneous application of two polycations. Such a... 

The nicotinic ACh receptor responds to the alkaloid nicotine contained in tobacco (many of the physiological effects of nicotine are based on this). The nicotinic receptor is ionotropic. Its properties are discussed in greater detail on p. 222. 

Since many toxins act on ion channels, they provide a wealth of chemical tools for studying the function of these channels. In fact, much of our current understanding of the properties of ion channels comes from studies utilizing only a small percentage of the highly potent and selective toxins that are now available. The toxins typically target voltage-sensitive ion channels, but a number of very useful toxins block ionotropic neurotransmitter receptors. Table 21-1 lists some of the toxins most commonly used in research, their mode of action, and their source. 

Second, while dopamine acts primarily at two receptor types, both of which produce slow potentials via G-protein-coupled mechanisms (i.e., metabotropic), glutamate mediates its effects at multiple postsynaptic receptors. While some glutamate receptors are metabotropic, the vast majority are coupled directly to ion channels (ionotropic). Different subtypes of glutamate receptors have different kinetic properties. 

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