Other experiments done by Malysz et al. have looked into ethanol effects on voltage-gated calcium channels on detrusor smooth muscle cells in guinea pigs. Perforated patch clamp technique was used having intracellular fluid inside the pipette and extracellular fluid in the bath with added 0.3% vol/vol (about 50-mM) ethanol. Ethanol decreased the current in DSM cells and induced muscle relaxation. Ethanol inhibits VGCCs and is involved in alcohol-induced relaxation of the urinary bladder. Agatoxin in spider venom Research on the desert grass spider, Agelenopsis aperta, has shown that agatoxins IVA and IVB found in their venom selectively block calcium channels. These agatoxins are found in other spider species as well. Desert grass spider bites to insects result in rapid paralysis, but bites to humans are not considered medically significant. Mechanism of action In the body's tissues, the concentration of calcium ions () outside cells is normally about 10,000-fold higher than the concentration inside cells. Embedded in the membrane of some cells are calcium channels. When these cells receive a certain signal, the channels open, letting calcium rush into the cell. The resulting increase in intracellular calcium has different effects in different types of cells. Calcium channel blockers prevent or reduce the opening of these channels and thereby reduce these effects. Several types of calcium channels occur, with a number of classes of blockers, but almost all of them preferentially or exclusively block the L-type voltage-gated calcium channel. Voltage-dependent calcium channels are responsible for excitation-contraction coupling of skeletal, smooth, and cardiac muscle and for regulating aldosterone and cortisol secretion in endocrine cells of the adrenal cortex. In the heart, they are also involved in the conduction of the pacemaker signals. CCBs used as medications primarily have four effects: By acting on vascular smooth muscle, they reduce contraction of the arteries and cause an increase in arterial diameter, a phenomenon called vasodilation (CCBs do not work on venous smooth muscle). By acting on cardiac muscles (myocardium), they reduce the force of contraction of the heart. By slowing down the conduction of electrical activity within the heart, they slow down the heart beat. By blocking the calcium signal on adrenal cortex cells, they directly reduce aldosterone production, which correlates to lower blood pressure. Since blood pressure is in intimate feedback with cardiac output and peripheral resistance, with relatively low blood pressure, the afterload on the heart decreases; this decreases how hard the heart