Junctional transverse tubules (TT) isolated from triads of rabbit skeletal muscle by centrifugation in an ion-free sucrose gradient were compared with membrane subfractions, predominantly derived from the free portion of TT, that had been purified from sarcoplasmic reticulum membrane contaminants by three different methods. The markers used were diagnostic membrane markers and the dihydropyridi...

The classical neurotransmitter acetylcholine (ACh) and the potential modulatory peptide somatostatin are colocalized in terminals of avian choroid neurons. We previously showed that exogenous somatostatin inhibits ACh release in the choroid coat (Gray et al., 1989b). In the present work we determine whether endogenous somatostatin plays a role in neuromodulation and what mechanisms are involved...

The effect of metabotropic glutamate receptor activation on Ca dihydropyridine (DHP)-sensitive channels recorded in the presence of 1 microM Bay K 8644 was examined on cultured cerebellar granule cells using the patch-clamp technique in the cell-attached configuration. Bath-applied agonist (trans-ACPD, 1S,3R-, and 1R,3S-ACPD isomers, and glutamate or quisqualate in the presence of CPP and CNQX)...

Strong depolarization and dihydropyridine agonists potentiate inward currents through native L-type Ca2+ channels, but the effect on outward currents is less clear due to the small size of these currents. Here, we examined potentiation of wild-type alpha1C and two constructs bearing mutations in conserved glutamates in the pore regions of repeats II and IV (E2A/E4A-alpha1C) or repeat III (E3K-a...

The effect of temperature and air humidity on the stability of 7 derivatives of 1,4-dihydropyridine (nifedipine, nisoldipine, nitrendipine, nimodipine, nicardipine, felodipine and amlodipine) in solid state has been studied by accelerated testing. Quantitative analysis of the compounds studied was made by UV spectrophotometry, identification of the thermodegradation products and reference to th...

The effects of dihydropyridine derivatives on contractile activity were examined in single fibers of frog skeletal muscles. Both nifedipine and Bay K 8644 enhanced twitch responses regardless of the presence or absence of Ca2+ without any effects on the resting membrane potential, evoked action potential and Ca2+ sensitivity of the contractile machinery. Twitch responses enhanced by Bay K 8644,...

BACKGROUND AND PURPOSE Calcium-channel blockers (CCBs) reduce systolic blood pressure and stroke-related mortality in stroke-prone spontaneously hypertensive rats (SPSHR). Brain ischemia is associated with loss of intracellular antioxidants. Increased formation of oxygen radicals and oxidation of LDL may enhance arterial vasoconstriction by various mechanisms. CCBs that also exert antioxidative...

Two deoxyglucose (DG) derivatives, (α,β)-2-deoxy-2-amino(ethylcarbamate)-D-glucose (ECB-DG) and (α,β)-2-deoxy-2-amino(1,2-dihydroxypropyl)-D-glucose (DHP-DG), were synthesized and radiolabeled successfully with [99mTc(H2O)3(CO)3]+ complex. [99mTc]-ECB-DG and [99mTc]-DHP-DG complexes were prepared (96% and 93% radiochemical purities respectively) by using 46 mCi of Na99mTcO4 in 1 mL saline. Radi...